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RFC 4011
Network Working Group S. Waldbusser
Request for Comments: 4011 Nextbeacon
Category: Standards Track J. Saperia
JDS Consulting, Inc.
T. Hongal
Riverstone Networks, Inc.
March 2005
Policy Based Management MIB
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in TCP/IP-based internets.
In particular, this MIB defines objects that enable policy-based
monitoring and management of Simple Network Management Protocol
(SNMP) infrastructures, a scripting language, and a script execution
environment.
Table of Contents
1. The Internet-Standard Management Framework .................. 3
2. Overview .................................................... 4
3. Policy-Based Management Architecture ........................ 4
4. Policy-Based Management Execution Environment ............... 10
4.1. Terminology ........................................... 10
4.2. Execution Environment - Elements of Procedure ......... 10
4.3. Element Discovery ..................................... 11
4.3.1. Implementation Notes .......................... 12
4.4. Element Filtering ..................................... 13
4.4.1. Implementation Notes .......................... 13
4.5. Policy Enforcement .................................... 13
4.5.1. Implementation Notes .......................... 14
5. The PolicyScript Language ................................... 14
5.1. Formal Definition ..................................... 15
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RFC 4011 Policy Based Management MIB March 2005
5.2. Variables ............................................. 18
5.2.1. The Var Class ................................. 19
5.3. PolicyScript QuickStart Guide ......................... 23
5.3.1. Quickstart for C Programmers .................. 25
5.3.2. Quickstart for Perl Programmers ............... 25
5.3.3. Quickstart for TCL Programmers ................ 25
5.3.4. Quickstart for Python Programmers ............. 26
5.3.5. Quickstart for JavaScript/ECMAScript/JScript
Programmers ................................... 26
5.4. PolicyScript Script Return Values ..................... 26
6. Index Information for `this element' ........................ 27
7. Library Functions ........................................... 28
8. Base Function Library ....................................... 29
8.1. SNMP Library Functions ................................ 29
8.1.1. SNMP Operations on Non-Local Systems .......... 30
8.1.2. Form of SNMP Values ........................... 32
8.1.3. Convenience SNMP Functions .................... 34
8.1.3.1. getVar() ............................ 34
8.1.3.2. exists() ............................ 34
8.1.3.3. setVar() ............................ 35
8.1.3.4. searchColumn() ...................... 36
8.1.3.5. setRowStatus() ...................... 38
8.1.3.6. createRow() ......................... 39
8.1.3.7. counterRate() ....................... 42
8.1.4. General SNMP Functions ........................ 44
8.1.4.1. newPDU() ............................ 45
8.1.4.2. writeVar() .......................... 45
8.1.4.3. readVar() ........................... 46
8.1.4.4. snmpSend() .......................... 47
8.1.4.5. readError() ......................... 48
8.1.4.6. writeBulkParameters() ............... 48
8.1.5. Constants for SNMP Library Functions .......... 49
8.2. Policy Library Functions .............................. 51
8.2.1. elementName() ................................. 51
8.2.2. elementAddress() .............................. 51
8.2.3. elementContext() .............................. 52
8.2.4. ec() .......................................... 52
8.2.5. ev() .......................................... 52
8.2.6. roleMatch() ................................... 52
8.2.7. Scratchpad Functions .......................... 53
8.2.8. setScratchpad() ............................... 55
8.2.9. getScratchpad() ............................... 56
8.2.10. signalError() ................................. 57
8.2.11. defer() ....................................... 57
8.2.12. fail() ........................................ 58
8.2.13. getParameters() ............................... 58
8.3. Utility Library Functions ............................. 59
8.3.1. regexp() ...................................... 59
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RFC 4011 Policy Based Management MIB March 2005
8.3.2. regexpReplace() ............................... 60
8.3.3. oidlen() ...................................... 60
8.3.4. oidncmp() ..................................... 60
8.3.5. inSubtree() ................................... 60
8.3.6. subid() ....................................... 61
8.3.7. subidWrite() .................................. 61
8.3.8. oidSplice() ................................... 61
8.3.9. parseIndex() .................................. 62
8.3.10. stringToDotted() .............................. 63
8.3.11. integer() ..................................... 64
8.3.12. string() ...................................... 64
8.3.13. type() ........................................ 64
8.3.14. chr() ......................................... 64
8.3.15. ord() ......................................... 64
8.3.16. substr() ...................................... 65
8.4. General Functions ..................................... 65
9. International String Library ................................ 65
9.1. stringprep() .......................................... 66
9.1.1. Stringprep Profile ............................ 66
9.2. utf8Strlen() .......................................... 67
9.3. utf8Chr() ............................................. 68
9.4. utf8Ord() ............................................. 68
9.5. utf8Substr() .......................................... 68
10. Schedule Table .............................................. 69
11. Definitions ................................................. 70
12. Relationship to Other MIB Modules ........................... 113
13. Security Considerations ..................................... 114
14. IANA Considerations ......................................... 117
15. Acknowledgements ............................................ 118
16. References .................................................. 118
16.1. Normative References .................................. 118
16.2. Informative References ................................ 119
Authors' Addresses .............................................. 120
Full Copyright Statement ........................................ 121
1. The Internet-Standard Management Framework
For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC 3410 [16].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB
module that is compliant to the SMIv2, which is described in STD 58,
RFC 2578 [2], STD 58, RFC 2579 [3], and STD 58, RFC 2580 [4].
Waldbusser, et al. Standards Track [Page 3]
RFC 4011 Policy Based Management MIB March 2005
2. Overview
Large IT organizations have developed management strategies to cope
with the extraordinarily large scale and complexity of today's
networks. In particular, they have tried to configure the network as
a whole by describing and implementing high-level business policies,
rather than manage device by device, where orders of magnitude more
decisions (and mistakes) may be made.
The following are examples of "business policies":
- All routers will run code version 6.2.
- On-site contractors will only be connected to ports that are
configured with special security restrictions.
- All voice over cable ports in California must provide free local
calling.
- Apply special forwarding to all ports whose customers have paid for
premium service.
Each of these policies could represent an action applied to hundreds
of thousands of variables.
To automate this practice, customers need software tools that will
implement business policies across their networks, as well as
standard protocols that will ensure that policies can be applied to
all of their devices, regardless of the vendor.
This practice is called Policy-Based Management. This document
defines managed objects for the Simple Network Management Protocol
that are used to distribute policies in a common form throughout the
network.
3. Policy-Based Management Architecture
Policy-based management is the practice of applying management
operations globally on all managed elements that share certain
attributes.
Policies are intended to express a notion of:
if (an element has certain characteristics) then (apply an
operation to that element)
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Policies take the following normal form:
if (policyCondition) then (policyAction)
A policyCondition is a script that results in a boolean to determine
whether an element is a member of a set of elements upon which an
action is to be performed.
A policyAction is an operation performed on an element or a set of
elements.
These policies are most often executed on or near managed devices
where the elements live (and thus their characteristics may be easily
inspected) and where operations on those elements will be performed.
A management station is responsible for distributing an
organization's policies to all the managed devices in the
infrastructure. The pmPolicyTable provides managed objects for
representing a policy on a managed device.
An element is an instance of a physical or logical entity and is
embodied by a group of related MIB variables, such as all the
variables for interface 7. This enables policies to be expressed
more efficiently and concisely. Elements can also model circuits,
CPUs, queues, processes, systems, etc.
Conceptually, policies are executed in the following manner:
for each element for which policyCondition returns true, execute
policyAction on that element
For example:
If (interface is fast ethernet) then (apply full-duplex mode)
If (interface is access) then (apply security filters)
If (circuit w/gold service paid for) then (apply special queuing)
Each unique combination of policy and element is called an execution
context. Within a particular execution context, the phrase 'this
element' is often used to refer to the associated element, as most
policy operations will be applied to 'this element'. The address of
'this element' contains the object identifier of any attribute of the
element, the SNMP context the element was discovered in, and the
address of the system on which the element was discovered.
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Policies can manage elements on the same system:
-----------------------------------------------------
| |
| Managed System |
| |
| |
| ------------------ Managed Elements |
| | | interfaces |
| | Policy Manager | manages... circuits |
| | | queues |
| ------------------ processes |
| ... |
| |
-----------------------------------------------------
or they can manage elements on other systems:
--------------------------
| Managed System |
-------------------------- | Managed Elements |
| | | interfaces |
| Management Station or | | circuits |
| Mid-Level Manager | | ... |
| | --------------------------
| ------------------ | manages...
| | Policy Manager | | --------------------------
| ------------------ | | Managed System |
| | | Managed Elements |
-------------------------- | interfaces |
| circuits |
| ... |
--------------------------
...
PolicyConditions have the capability of performing comparison
operations on SNMP variables, logical expressions, and other
functions. Many device characteristics are already defined in MIB
Modules and are easy to include in policyCondition expressions
(ifType == ethernet, frCircuitCommittedBurst < 128K, etc). However,
there are important characteristics that aren't currently in MIB
objects, and, worse, it is not current practice to store this
information on managed devices. Therefore, this document defines MIB
objects for this information. To meet today's needs there are three
missing areas: roles, capabilities, and time.
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Roles
A role is an administratively specified characteristic of a managed
element. As a selector for policies, it determines the applicability
of the policy to a particular managed element.
Some examples of roles are political, financial, legal, geographical,
or architectural characteristics, typically not directly derivable
from information stored on the managed system. For example, "paid
for premium service" or "is plugged into a UPS" are examples of
roles, whereas the "percent utilization of a link" would not be.
Some types of information one would put into a role include the
following:
political - describes the role of a person or group of people, or of
a service that a group of people uses. Examples:
executive, sales, outside-contractor, customer.
If (attached user is executive) then (apply higher bandwidth)
If (attached user is outside-contractor) then (restrict access)
financial/legal - describes what financial consideration was
received. Could also include contractual or legal
considerations. Examples: paid, gold, free, trial,
demo, lifeline.
If (gold service paid for) then (apply special queuing)
geographical - describes the location of an element. Examples:
California, Headquarters, insecure conduit.
If (interface leaves the building) then (apply special security)
architectural - describes the network architects "intent" for an
element. Examples: backup, trunk.
If (interface is backup) then (set ifAdminStatus = down)
Roles in this model are human-defined strings that can be
referenced by policy code. The role table in this MIB may be used
to assign role strings to elements and to view all role string
assignments. Implementation-specific mechanisms may also be used
to assign role strings; however, these assignments must be visible
in the role table. Multiple roles may be assigned to each
element. Because policy code has access to data in MIB objects
that represent the current state of the system and (in contrast)
role strings are more static, it is recommended that role strings
not duplicate information available in MIB objects. Role strings
generally should be used to describe information not accessible in
MIB objects.
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Policy scripts may inspect role assignments to make decisions
based on whether an element has a particular role assigned to it.
The pmRoleTable allows a management station to learn what roles
exist on a managed system. The management station may choose not
to install policies that depend on a role that does not exist on
any elements in the system. The management station can then
register for notifications of new roles. Upon receipt of a
pmNewRoleNotification, it may choose to install new policies that
make use of that new role.
Capabilities
The capabilities table allows a management station to learn what
capabilities exist on a managed system. The management station
may choose not to install policies that depend on a capability
that does not exist on any elements in the system. The management
station can then register for notifications of new capabilities.
Upon receipt of a pmNewCapabilityNotification, it may choose to
install new policies that make use of that new capability.
Time
Managers may wish to define policies that are intended to apply
for certain periods of time. This might mean that a policy is
installed and is dormant for a period of time, becomes ready, and
then later goes dormant again. Sometimes these time periods will
be regular (Monday-Friday 9-5), and sometimes ad hoc. This MIB
provides a schedule table that can schedule when a policy is ready
and when it is dormant.
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A policy manager contains the following:
-------------------------------------------------------
| Policy Manager |
| |
| ---------------------------------------- |
| | Agent | |
| | | |
| | --------------------------------- | |
| | | Policy Download and Control | | |
| | | pmPolicyTable | | |
| | | pmElementTypeRegTable | | |
| | | pmSchedTable | | |
| | --------------------------------- | |
| | | |
| | --------------------------------- | |
| | | Policy Environment Control | | |
| | | pmRoleTable | | |
| | | pmCapabilitiesTables | | |
| | --------------------------------- | |
| | | |
| | --------------------------------- | |
| | | Policy Monitoring | | |
| | | pmTrackingTables | | |
| | | pmDebuggingTable | | |
| | --------------------------------- | |
| ---------------------------------------- |
| |
| -------------------------------- |
| | Execution Environment | |
| | | |
| | ----------------------- | |
| | | Policy Scheduler | | |
| | ----------------------- | |
| | ----------------------- | |
| | | Language | | |
| | ----------------------- | |
| | ----------------------- | |
| | | Function Library | | |
| | ----------------------- | |
| -------------------------------- |
-------------------------------------------------------
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4. Policy-Based Management Execution Environment
4.1. Terminology
Active Schedule - A schedule specifies certain times that it will be
considered active. A schedule is active during those times.
Valid Policy - A valid policy is a policy that is fully configured
and enabled to run. A valid policy may run unless it is linked to
a schedule entry that says the policy is not currently active.
Ready Policy - A ready policy is a valid policy that either has no
schedule or is linked to a schedule that is currently active.
Precedence Group - Multiple policies can be assigned to a precedence
group with the resulting behavior that for each element, of the
ready policies that match the condition, only the one with the
highest precedence value will be active. For example, if there is
a default bronze policy that applies to any interface and a
special policy for gold interfaces, the higher precedence of the
gold policy will ensure that it is run on gold ports and that the
bronze policy isn't.
Active Execution Context - An active execution context is a pairing
of a ready policy with an element that matches the element type
filter and the policy condition. If there are multiple policies
in the precedence group, it is also necessary that no higher
precedence policy in the group match the policy condition.
Run-Time Exception (RTE) - A run-time exception is a fatal error
caused in language or function processing. If, during the
invocation of a script, a run-time exception occurs, execution of
that script is immediately terminated. If a policyCondition
experiences a run-time exception while processing an element, the
element is not matched by the condition and the associated action
will not be run on that element. A run-time exception can cause
an entry to be added to the pmDebuggingTable and will be reflected
in the pmTrackingPEInfo object.
4.2. Execution Environment - Elements of Procedure
There are several steps performed in order to execute policies in
this environment:
- Element Discovery
- Element Filtering
- Policy Enforcement
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4.3. Element Discovery
An element is an instance of a physical or logical entity. Examples
of elements include interfaces, circuits, queues, CPUs, and
processes. Sometimes various attributes of an entity will be
described through tables in several standard and proprietary MIB
Modules. As long as the indexing is consistent between these tables,
the entity can be modeled as one element. For example, the ifTable
and the dot3Stats table both contain attributes of interfaces and
share the same index (ifIndex), therefore they can be modeled as one
element type.
The Element Type Registration table allows the manager to learn what
element types are being managed by the system and to register new
types, if necessary. An element type is registered by providing the
OID of an SNMP object (i.e., without the instance). Each SNMP
instance that exists under that object is a distinct element. The
index part of the discovered OID will be supplied to policy
conditions and actions so that this code can inspect and configure
the element. The agent can determine the index portion of discovered
OIDs based on the length of the pmElementTypeRegOIDPrefix for the
portion of the MIB that is being retrieved. For example, if the
OIDPrefix is 'ifEntry', which has 9 subids, the index starts on the
11th subid (skipping the subidentifier for the column; e.g.,
ifSpeed).
For each element that is discovered, the policy condition is called
with the element's name as an argument to see whether the element is
a member of the set the policy acts upon.
Note that agents may automatically configure entries in this table
for frequently used element types (interfaces, circuits, etc.). In
particular, it may configure elements for which discovery is
optimized in one or both of the following ways:
1. The agent may discover elements by scanning internal data
structures as opposed to issuing local SNMP requests. It is
possible to recreate the exact semantics described in this table
even if local SNMP requests are not issued.
2. The agent may receive asynchronous notification of new elements
(for example, "card inserted") and use that information to create
elements instantly rather than through polling. A similar feature
might be available for the deletion of elements.
Note that upon restart, the disposition of agent-installed entries is
described by the pmPolicyStorageType object.
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A special element type "0.0" represents the "system element". "0.0"
represents the single instance of the system itself and provides an
execution context for policies to operate on "the system" and on MIB
objects modeled as scalars. For example, "0.0" gives an execution
context for policy-based selection of the operating system code
version (likely modeled as a scalar MIB object). The element type
"0.0" always exists. As a consequence, no actual discovery will take
place and the pmElementTypeRegMaxLatency object will have no effect
for the "0.0" element type. However, if the "0.0" element type is
not registered in the table, policies will not be executed on the
"0.0" element.
If the agent is discovering elements by polling, it should check for
new elements no less frequently than pmElementTypeRegMaxLatency would
dictate. When an element is first discovered, all policyConditions
are run immediately, and policyConditions that match will have the
associated policyAction run immediately. Subsequently, the
policyCondition will be run regularly for the element, with no more
than pmPolicyConditionMaxLatency milliseconds elapsing between each
invocation. Note that if an implementation has the ability to be
alerted immediately when a particular type of element is created, it
is urged to discover that type of element in this fashion rather than
through polling, resulting in immediate configuration of the
discovered element.
4.3.1. Implementation Notes
Note that although the external behavior of this registration process
is defined in terms of the walking of MIB tables, implementation
strategies may differ. For example, commonly used element types
(such as interface) may have purpose-built element discovery
capability built-in and advertised to managers through an entry in
the pmElementTypeRegTable.
Before registering an element type, a manager is responsible for
inspecting the table to see whether it is already registered (either
by the agent or by another manager). Note that entries that differ
only in the last subid (which specifies which object is an entry) are
effectively duplicates and should be treated as such by the manager.
The system that implements the Policy-Based Management MIB may not
have knowledge of the format of object identifiers in other MIB
Modules. Therefore it is inappropriate for it to check these OIDs
for errors. It is the responsibility of the management station to
register well-formed object identifiers. For example, if an extra
sub-identifier is supplied when the ifTable is registered, no
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elements will be discovered. Similarly, if a sub-identifier is
missing, every element will be discovered numerous times (once per
column) and none of the element addresses will be well formed.
4.4. Element Filtering
The first step in executing a policy is to see whether the policy is
ready to run based on its schedule. If the pmPolicySchedule object
is equal to zero, there is no schedule defined, and the policy is
always ready. If the pmPolicySchedule object is non-zero, then the
policy is ready only if the referenced schedule group contains at
least one valid schedule entry that is active at the current time.
If the policy is ready, the next step in executing a policy is to see
which elements match the policy condition. The policy condition is
called once for each element and runs to completion. The element's
name is the only argument that is passed to the condition code for
each invocation. No state is remembered within the policy script
from the previous invocation of 'this element' or from the previous
invocation of the policy condition, except for state accessible
through library functions. Two notable examples of these are the
scratchpad functions, which explicitly provide for storing state, and
the SNMP functions, which can store state in local or remote MIB
objects. If any run-time exception occurs, the condition will
terminate immediately for 'this element'. If the condition returns
non-zero, the corresponding policy action will be executed for 'this
element'.
If an element matches a condition and it had not matched that
condition the last time it was checked (or if it is a newly
discovered element), the associated policyAction will be executed
immediately. If the element had matched the condition at the last
check, it will remain in the set of elements whose policyAction will
be run within the policyActionMaxLatency.
4.4.1. Implementation Notes
Whether policy conditions are multi-tasked is an implementation-
dependent matter. Each condition/element combination is conceptually
its own process and can be scheduled sequentially, or two or more
could be run simultaneously.
4.5. Policy Enforcement
For each element that has returned non-zero from the policy
condition, the corresponding policy action is called. The element's
name is the only argument that is passed to the policy action for
each invocation. Except for state accessible from library functions,
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no state is remembered from the policy condition evaluation, or from
the previous condition/action invocation of 'this element' or from
the previous invocation of the policy condition or action on any
other element. If any run-time exception occurs, the action will
terminate immediately for 'this element'.
4.5.1. Implementation Notes
How policy actions are multi-tasked is an implementation-dependent
matter. Each condition/element combination is conceptually its own
process and can be scheduled sequentially, or two or more could be
run simultaneously.
5. The PolicyScript Language
Policy conditions and policy actions are expressed with the
PolicyScript language. The PolicyScript language is designed to be a
small interpreted language that is simple to understand and
implement; it is designed to be appropriate for writing small scripts
that make up policy conditions and actions.
PolicyScript is intended to be familiar to programmers that know one
of several common languages, including Perl and C. Nominally,
policyScript is a subset of the C language; however, it was desirable
to have access to C++'s operator overloading (solely to aid in
documenting the language). Therefore, PolicyScript is defined
formally as a subset of the C++ language in which many of the
operators are overloaded as part of the "var" class. Note, however,
that a PolicyScript program cannot further overload operators, as the
syntax to specify overloading is not part of the PolicyScript syntax.
A subset was used to provide for easy development of low-cost
interpreters of PolicyScript and to take away language constructs
that are peculiar to the C/C++ languages. For example, it is
expected that both C and Perl programmers will understand the
constructs allowed in PolicyScript.
Some examples of the C/C++ features that are not available are
function definitions, pointer variables, structures, enums, typedefs,
floating point and pre-processor functions (except for comments).
This language is formally defined as a subset of ISO C++ [10] but
only allows constructs that may be expressed in the Extended Backus-
Naur Form (EBNF) documented here. This is because although EBNF
doesn't fully specify syntactical rules (it allows constructs that
are invalid) and doesn't specify semantic rules, it can successfully
be used to define the subset of the language that is required for
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conformance to this specification. Unless explicitly described
herein, the meaning of any construct expressed in the EBNF can be
found by reference to the ISO C++ standard.
The use of comments and newlines are allowed and encouraged in order
to promote readability of PolicyScript code. Comments begin with
'/*' and end with '*/' or begin with '//' and go until the end of the
line.
One subset is not expressible in the EBNF syntax: all variables
within an instance of a PolicyScript script are within the same
scope. In other words, variables defined in a block delimited with
'{' and '}' are not in a separate scope from variables in the
enclosing block.
PolicyScript code must be expressed in the ASCII character set.
In the EBNF used here, terminals are character set members (singly or
in a sequence) that are enclosed between two single-quote characters
or described as a phrase between '<' and '>' characters.
Nonterminals are a sequence of letters and underscore characters. A
colon (:) following a nonterminal introduces its definition, a
production. In a production, a '|' character separates alternatives.
The '(' and ')' symbols group the enclosed items. The '[' and ']'
symbols indicate that the enclosed items are optional. A '?' symbol
following an item indicates that the item is optional. A '*' symbol
following an item indicates that the item is repeated zero, one, or
more times. A '+' symbol following an item indicates that the item
is repeated one or more times. The symbol '--' begins a comment that
ends at the end of the line.
5.1. Formal Definition
The PolicyScript language follows the syntax and semantics of ISO C++
[10], but is limited to that which can be expressed in the EBNF
below.
The following keywords are reserved words and cannot be used in any
policy script. This prevents someone from using a common keyword in
another language as an identifier in a script, thereby confusing the
meaning of the script. The reserved words are:
auto, case, char, const, default, do, double, enum, extern, float,
goto, inline, int, long, register, short, signed, sizeof, static,
struct, switch, typedef, union, unsigned, void, and volatile.
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Any syntax error, use of a reserved keyword, reference to an unknown
identifier, improper number of function arguments, error in coercing
an argument to the proper type, exceeding local limitations on string
length, or exceeding local limitations on the total amount of storage
used by local variables will cause an RTE.
PolicyScript permits comments using the comment delimiters, '/*' to
'*/', or the start of comment symbol '//'.
-- Lexical Grammar
letter: '_' | 'a' | 'b' | 'c' | 'd' | 'e' | 'f'
| 'g' | 'h' | 'i' | 'j' | 'k' | 'l' | 'm'
| 'n' | 'o' | 'p' | 'q' | 'r' | 's' | 't'
| 'u' | 'v' | 'w' | 'x' | 'y' | 'z'
| 'A' | 'B' | 'C' | 'D' | 'E' | 'F'
| 'G' | 'H' | 'I' | 'J' | 'K' | 'L' | 'M'
| 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T'
| 'U' | 'V' | 'W' | 'X' | 'Y' | 'Z'
digit: '0' | '1' | '2' | '3' | '4'
| '5' | '6' | '7' | '8' | '9'
non_zero: '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
oct_digit: '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7'
hex_digit: digit | 'a' | 'b' | 'c' | 'd' | 'e' | 'f'
| 'A' | 'B' | 'C' | 'D' | 'E' | 'F'
escape_seq: '\'' | '\"' | '\?' | '\\'
| '\a' | '\b' | '\f' | '\n'
| '\r' | '\t' | '\v'
| '\' oct_digit+ | '\x' hex_digit+
non_quote: Any character in the ASCII character set
except single quote ('), double quote ("),
backslash ('\'), or newline.
c_char: non_quote | '"' | escape_seq
string_literal: '"' s_char* '"'
s_char: non_quote | ''' | escape_seq
char_constant: ''' c_char '''
decimal_constant: non_zero digit*
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octal_constant: '0' oct_digit*
hex_constant: ( '0x' | '0X' ) hex_digit+
integer_constant: decimal_constant | octal_constant | hex_constant
identifier: letter ( letter | digit )*
-- Phrase Structure Grammar
-- Expressions
primary_expr: identifier | integer_constant | char_constant
| string_literal | '(' expression ')'
postfix_expr: primary_expr
| identifier '(' argument_expression_list? ')'
| postfix_expr '++'
| postfix_expr '--'
| postfix_expr '[' expression ']'
argument_expression_list:
assignment_expr
| argument_expression_list ',' assignment_expr
unary_expr: postfix_expr | unary_op unary_expr
unary_op: '+' | '-' | '~' | '!' | '++' | '--'
binary_expr: unary_expr | binary_expr binary_op unary_expr
binary_op: '||' | '&&' | '|' | '^' | '&' | '!='
| '==' | '>=' | '<=' | '>' | '<' | '>>'
| '<<' | '-' | '+' | '%' | '/' | '*'
assignment_expr: binary_expr
| unary_expr assignment_op assignment_expr
assignment_op: '=' | '*=' | '/=' | '%=' | '+=' | '-='
| '<<=' | '>>=' | '&=' | '^=' | '|='
expression: assignment_expr | expression ',' assignment_expr
-- Declarations
declaration: 'var' declarator_list ';'
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declarator_list: init_declarator
| declarator_list ',' init_declarator
init_declarator: identifier [ '=' assignment_expr ]
-- Statements
statement: declaration
| compound_statement
| expression_statement
| selection_statement
| iteration_statement
| jump_statement
compound_statement: '{' statement* '}'
expression_statement: expression? ';'
selection_statement:
'if' '(' expression ')' statement
| 'if' '(' expression ')' statement 'else' statement
iteration_statement:
'while' '(' expression ')' statement
| 'for' '(' expression? ';' expression? ';' expression? ')'
statement
jump_statement: 'continue' ';'
| 'break' ';'
| 'return' expression? ';'
-- Root production
PolicyScript: statement*
5.2. Variables
To promote shorter scripts and ease in writing them, PolicyScript
provides a loosely typed data class, "var", that can store both
integer and string values. The native C++ types (char, int, etc.)
are thus unnecessary and have not been carried into the subset that
comprises this language. The semantics of the "var" type are modeled
after those of ECMAScript[17].
For example:
var number = 0, name = "IETF";
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This language will be executed in an environment where the following
typedef is declared. (Note that this typedef will not be visible in
the policyCondition or policyAction code.)
typedef ... var;
Although this declaration is expressed here as a typedef, the
'typedef' keyword itself is not available to be used in PolicyScript
code.
5.2.1. The Var Class
A value is an entity that takes on one of two types: string or
integer.
The String type is the set of all finite ordered sequences of zero or
more 8-bit unsigned integer values ("elements"). The string type can
store textual data as well as binary data sequences. Each element is
considered to occupy a position within the sequence. These positions
are indexed with nonnegative integers. The first element (if any) is
at position 0, the next element (if any) at position 1, and so on.
The length of a string is the number of elements (i.e., 8-bit values)
within it. The empty string has length zero and therefore contains
no elements.
The integer type is the set of all integer values in the range
-9223372036854775808 (-2^63) to 18446744073709551615 (2^64-1). If an
integer operation would cause a (positive) overflow, then the result
is returned modulo 2^64. If an integer operation would cause a
(negative) underflow, then the result is undefined. Integer division
rounds toward zero.
Prior to initialization, a var object has type String and a length of
zero.
The policy script runtime system performs automatic type conversion
as needed. To clarify the semantics of certain constructs it is
useful to define a set of conversion operators: ToInteger(),
ToString(), ToBoolean(), and Type(). These operators are not a part
of the language; they are defined here to aid the specification of
the semantics of the language. The conversion operators are
polymorphic; that is, they can accept a value of any standard type.
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ToInteger
The operator ToInteger converts its argument to a value of type
Integer according to the following table:
Integer The result equals the input argument
(no conversion).
String See grammar and note below.
integer_constant The result equals the input argument
(no conversion).
string_literal See grammar and note below.
char_constant See grammar and note below.
ToInteger Applied to Strings
ToInteger applied to the String Type string_literal and to
char_constants applies the following grammar to the input. If the
grammar cannot interpret the string as an expansion of
numeric_string, then an RTE is generated. Note that a numeric_string
that is empty or contains only white space is converted to 0.
-- EBNF for numeric_string
numeric_string : white_space* numeric? white_space*
white_space : <TAB> | <SP> | <NBSP> | <FF> | <VT>
| <CR> | <LF> | <LS> | <PS> | <USP>
numeric : signed_decimal | hex_constant | octal_constant |
enum_decimal
signed_decimal: [ '-' | '+' ] decimal_constant
enum_decimal: [ letter | digit | '-' ]* '(' decimal_constant ')'
-- decimal_constant, hex_constant, and octal_constant are defined
-- in the PolicyScript EBNF described earlier.
Note that when the enum_decimal form is converted, the sequence of
characters before the parenthesis and the pair of parenthesis
themselves are completely ignored, and the decimal_constant inside
the parenthesis is converted. Thus, "frame-relay(32)" translates to
the integer 32.
Although this will make the script more readable than using the
constant "32", the burden is on the code writer to be accurate, as
"ethernet-csmacd(32)" and "frame-relay(999)" will also be accepted.
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ToString
The operator ToString converts its argument to a value of type String
according to the following table:
Integer Return the string containing the decimal
representation of the input argument in
the form of signed_decimal, except that
no leading '+' will be used.
String Return the input argument (no conversion)
integer_constant Return the string containing the decimal
representation of the input argument in the
form of signed_decimal except that no
leading '+' will be used.
string_literal Return the input argument (no conversion)
char_constant Return the string of length one containing
the value of the input argument.
ToBoolean
The operator ToBoolean converts its argument to a value of type
Integer according to the following table:
Integer The result is 0 if the argument is 0.
Otherwise the result is 1.
String The results is 0 if the argument is the
empty string. Otherwise the result is 1.
integer_constant The result is 0 if the argument is 0.
Otherwise the result is 1.
string_literal The result is 0 if the argument is the
empty string. Otherwise the result is 1.
char_constant The result is 1.
Operators
The rules below specify the type conversion rules for the various
operators.
A++: A = ToInteger(A); A++;
A--: A = ToInteger(A); A--;
++A: A = ToInteger(A); ++A;
--A: A = ToInteger(A); --A;
+A: ToInteger(A);
-A: -1 * ToInteger(A);
~A: ToInteger(A);
!A: !ToBoolean(A);
A * B, A - B, A & B, A ^ B , A | B, A << B, A >> B:
ToInteger(A) <operator> ToInteger(B)
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A / B, A % B:
if (ToInteger(B) == 0)
RTE, terminate;
else
ToInteger(A) <operator> ToInteger(B)
A + B:
if (Type(A) == String || Type(B) == String)
ToString(A) concatenated with ToString(B)
else
A + B
Compound Assignment (<operator>=):
Simply follow rules above. Note that type of LHS (Left
Hand Side) may be changed as a result.
A < B, A > B, A <= B, A >= B, A == B, A != B:
if (Type(A) == String && Type(B) == String)
lexically compare strings with strcmp() logic
else
ToInteger(A) <operator> ToInteger(B)
A && B:
if (ToBoolean(A))
ToBoolean(B);
else
false;
A || B:
if (ToBoolean(A))
true;
else
ToBoolean(B);
if(A):
if (ToBoolean(A))
while(A):
while(ToBoolean(A))
for(...; A; ...):
for(...; ToBoolean(A); ...)
A[B] as a RHS (Right Hand Side) value:
if (Type(A) != String
|| ToInteger(B) >= strlen(A))
RTE, terminate;
A[ ToInteger(B) ]
The contents are returned as a string of length one
A[B] = C as a LHS value:
if (Type(A) != String
|| ToInteger(B) >= strlen(A))
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RTE, terminate;
if (strlen(ToString(C)) == 0)
RTE, terminate
A[ ToInteger(B) ] = First octet of ToString(C)
Note that this is only applicable in a simple assignment.
For example, in the expression
"getVar("ifSpeed.1") < 128000"
getVar always returns a string and '128000' is implicitly an integer.
The rules for '<' dictate that if either argument is an integer then
a 'numeric less than' is performed on ToInteger(A) and ToInteger(B).
If "getVar("ifSpeed.1")" returns "64000", the expression can be
translated to:
ToInteger("64000") < ToInteger(128000); or,
64000 < 128000; or,
True
5.3. PolicyScript QuickStart Guide
PolicyScript is designed so that programmers fluent in other
languages can quickly begin to write scripts.
One way to become familiar with a language is to see it in action.
The following nonsensical script exercises most of the PolicyScript
constructs (though it skips some usage options and many arithmetic
operators).
var x, index = 7, str = "Hello World", oid = "ifSpeed.";
x = 0;
while(x < 10){
if (str < "Goodbye") /* string comparison */
continue;
else
break;
x++;
}
if (oidlen(oid) == 10)
oid += "." + index; // append index to oid
for(x = 0; x < 7; x++){
str += "a";
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var y = 12;
index = ((x * 7) + y) % 3;
if (str[6] == 'W')
return index;
}
return;
The following examples are more practical:
For a condition:
// Return 1 if this is an interface and it is tagged
// with the role "gold"
return (inSubtree(elementName(), "ifEntry")
&& roleMatch("gold"))
A condition/action pair:
First, register the Host Resources MIB hrSWRunEntry as a new element
in the pmElementTypeRegTable. This will cause the policy to run for
every process on the system. The token '$*' will be replaced by the
script interpreter with a process index (see Section 7 for a
definition of the '$*' token).
The condition:
// if it's a process and it's an application and it's
// consumed more than 5 minutes of CPU time
return (inSubtree(elementName(), "hrSWRunEntry")
&& getVar("hrSWRunType.$*") == 4 // app, not OS or driver
&& getVar("hrSWRunPerfCPU.$*") > 30000) // 300 seconds
The action:
// Kill it
setVar("hrSWRunStatus.$*", 4, Integer); // invalid(4) kills it
A more substantial action to start an RMON2 host table on interfaces
that match the condition:
var pdu, index;
pdu = newPDU();
writeVar(pdu, 0, "hlHostControlDataSource.*",
"ifIndex." + ev(0), Oid);
writeVar(pdu, 1, "hlHostControlNlMaxDesiredEntries.*", 1000,
Integer);
writeVar(pdu, 2, "hlHostControlAlMaxDesiredEntries.*", 1000,
Integer);
writeVar(pdu, 3, "hlHostControlOwner.*", "policy", String);
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writeVar(pdu, 4, "hlHostControlStatus.*", "active(1)", Integer);
if (createRow(pdu, 5, 4, 20, 65535, index) == 0
|| index == -1)
return;
Because PolicyScript is a least common denominator, it contains
nothing that would astonish programmers familiar with C, C++, Perl,
Tcl, JavaScript, or Python. Although a new programmer may attempt to
use language constructs that aren't available in PolicyScript, s/he
should be able to understand any existing PolicyScript and will
likely know how to use anything that is valid in PolicyScript. The
lists below quickly enumerate the changes of note for programmers
coming from some particular languages. These lists won't describe
the unavailable constructs, but it is easy to see from the definition
above what is available.
5.3.1. Quickstart for C Programmers
- Character constants (i.e., 'c') are treated as one-character
strings, not as integers. So operations such as ('M' - 'A') or (x
+ 'A') will not perform as expected.
- Functions can change the value of arguments even though they are
not pointers (or called like '&arg').
- All variables are in the same scope.
5.3.2. Quickstart for Perl Programmers
- Comments are '/* comment */' and '// till end of line', not '#'.
- No need to put a '$' in front of variables.
- Strings are compared with ==, <=, <, etc. (details in Sec. 6.2.1).
- Strings are concatenated with '+' (details in Sec. 6.2.1).
- No variable substitution in "" strings. '' strings are 1 char
only.
- Variables must be declared before use (but no type is necessary).
- All variables are in the same scope.
5.3.3. Quickstart for TCL Programmers
- Comments are '/* comment */' and '// till end of line', not '#'.
- No need to put a '$' in front of variables.
- Function calls are func-name(arg1, arg2, ...).
- Square braces [] don't interpret their contents.
- Double quotes "" surround a string, but no substitutions are
performed ("" is like { } in TCL ).
- Statements are terminated by a semicolon (;).
- Instead of "Set a b", use "b = a;".
- Strings are concatenated with '+' (details in Sec. 6.2.1).
- All variables are in the same scope.
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5.3.4. Quickstart for Python Programmers
- Comments are '/* comment */' and '// till end of line', not '#'.
- Single quotes can be used only for single-character strings ('a').
- Indentation doesn't matter. Braces { } define blocks.
- Variables must be declared before use (but no type is necessary).
- The expressions for if and while are always surrounded by
parenthesis, as in "if (x < 5)".
- 'for' syntax is "for(expression; expression; expression)" (see
EBNF).
- All variables are in the same scope.
5.3.5. Quickstart for JavaScript/ECMAScript/JScript Programmers
- Variables must be declared before use.
- Functions can change the value of arguments.
- All variables are in the same scope.
5.4. PolicyScript Script Return Values
A PolicyScript script execution is normally ended by the execution of
a return statement, or by having the flow of execution reach the end
of the final statement in the script. A normal script execution
always returns a Boolean value. If no explicit value is specified in
the return statement, or if the flow of control proceeds through the
end of the script, the return value is implicitly zero. If an
expression is provided with the return statement, the expression is
evaluated, and the result of the expression is implicitly converted
with the ToBoolean operator before being returned to the script
execution environment.
The return value of a policyCondition script is used to determine
whether the associated policyAction script is executed. If the
returned value is zero, the associated policyAction script is not
executed. If the returned value is one, the associated policyAction
script will be executed.
The return value of a policyAction script is ignored.
An RTE or invocation of the fail() function will cause the return
value of the script to be set to zero. Note however, that execution
of the defer() or fail() functions may set the defer attribute so
that the lower precedence script may be executed. This is
independent of the return value of the policy script execution.
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6. Index Information for 'this element'
PolicyScript code needs a convenient way to get the components of the
index for 'this element' so that they can perform SNMP operations on
it or on related elements.
Two mechanisms are provided.
1. For all OID input parameters to all SNMP Library Functions (but
not OID utility functions), the token "$n" ('$' followed by an
integer between 0 and 128) can be used in place of any decimal
sub-identifier. This token is expanded by the agent at execution
time to contain the nth subid of the index for the current
element. For example, if the element is interface 7, and the
objectIdentifier is "1.3.6.1.2.1.2.2.1.3.$0", it will be expanded
to "1.3.6.1.2.1.2.2.1.3.7". The special token "$*" is expanded to
contain all of the subidentifiers of the index of the current
element, separated by '.' characters.
It is an RTE if a token is specified that is beyond the length of
the index for the current element.
Note that the "$n" convention is only active within strings.
2. The ec() and ev() functions allow access to the components of the
index for 'this element'. ec() takes no argument and returns the
number of index components that exist. ev() takes an integer
argument specifying which component of the index (numbered
starting at 0) and returns an integer containing the value of the
n'th subidentifier. Refer to the Library functions section for
the complete definition of ec() and ev().
For example, if 'this element' is frCircuitDLCI.5.57
(ifIndex = 5, DLCI = 57)
then ec() returns 2
ev(0) returns 5
ev(1) returns 57
This is helpful when one wishes to address a related element.
Extending the previous example, to find the port speed of the
port, the circuit (above) runs over:
portSpeed = getVar("ifSpeed." + ev(0));
A script may check the type of 'this element' by calling the
elementName() function. Although it is possible to write a script
that will work with different types of elements, many scripts will
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assume a particular element type and will work incorrectly if used
on different element types.
7. Library Functions
Library functions are built-in functions available primarily to
provide access to information on the local system or to manipulate
this information more efficiently. A group of functions is organized
into a library, the unit of conformance for function implementation.
In order to claim conformance to a library, an implementation must
implement all functions in a library to the specifications of the
library.
In order for a management station or a condition or action to
understand whether a certain library of functions is implemented,
each library will have a name that it registers in the role table as
a characteristic of the system element ("0.0") in the default SNMP
context. Thus, conformance to a library can be tested with the
roleMatch library function (in the base library) with the call
roleMatch ("libraryName", "0.0").
Note that in the descriptions of these functions below, the function
prototype describes the type of argument expected. Even though
variables are not declared with a particular type, their contents
must be appropriate for each function argument. If the type is
variable, the keyword 'var' will be used. If only a string is
appropriate, the keyword 'string' will be used. If only an integer
is appropriate, the keyword 'integer' will be used. If the argument
is declared as 'string' or 'integer' and a value of a different type
is passed, the argument will be coerced with ToInteger() or
ToString(). Any failure of this coercion will cause an RTE (in
particular for ToInteger(), which will fail if its string-valued
argument is not a well-formed integer).
In the function prototype, if the '&' character precedes the
identifier for an argument, that argument may be modified by the
function (e.g., "integer &result, ...)"). Arguments without the '&'
character cannot be modified by the function. In a script,
modifiable arguments don't have to be preceded by a '&'. It is an
RTE if a constant is passed to a modifiable function argument
(regardless of whether the function actually writes to the argument).
In the function prototype, the '[' and ']' characters surround
arguments that are optional. In PolicyScript code, the optional
argument may only be included if all optional arguments to the left
of it are included. The function may place restrictions on when an
optional argument must, or must not, be included.
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In the function prototype, if a type is listed before the name of the
function, the function returns a value of that type. If no type is
listed, the function returns no value.
8. Base Function Library
A standard base library of functions is available to all systems that
implement this specification. This library is registered with the
name "pmBaseFunctionLibrary". Although the specification of this
library is modularized into 4 separate sections, conformance to the
library requires implementation of all functions in all sections.
The sections are:
- SNMP library functions
- Policy library functions
- Utility functions
- Library Functions
8.1. SNMP Library Functions
Two sets of SNMP Library functions are available with different
situations in mind:
- Convenience SNMP Functions
In an effort to keep simple things simple, these functions are easy
to use and code that is easy to understand. These functions will
suffice for the majority of situations, where a single variable is
referenced and the desired error recovery is simply (and
immediately) to give up (and move to the next policy-element
combination). In more complex cases, the General SNMP Functions
can be used at the cost of several times the code complexity.
The convenience SNMP functions are getVar, exists, setVar,
setRowStatus, createRow, counterRate, and searchColumn.
- General SNMP Functions
The General SNMP functions allow nearly any legal SNMP Message to
be generated, including those with multiple varbinds, getNext
operations, notifications, and messages with explicit addressing or
security specifications.
The general SNMP functions are writeVar, readVar, snmpSend,
readError, and writeBulkParameters.
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8.1.1. SNMP Operations on Non-Local Systems
From time to time, a script may have to perform an operation on a
different SNMP system than that on which 'this element' resides.
Scripts may also have to specify the use of alternate security
parameters. In order to do this, the following optional arguments
are provided for the SNMP library functions:
snmp-function(...[, integer mPModel,
string tDomain, string tAddress,
integer secModel, string secName,
integer secLevel, string contextEngineID
])
For example:
getVar("sysDescr.0", "", SNMPv3, "transportDomainUdpIpv4",
"192.168.1.1:161", USM, "joe", NoAuthNoPriv);
The use of these arguments is denoted in function definitions by the
keyword 'NonLocalArgs'. The definitions of these arguments are as
follows:
'mPModel' is the integer value of the SnmpMessageProcessingModel
to use for this operation.
'tDomain' is a string containing an ASCII dotted-decimal object
identifier representing the transport domain to use for this
operation.
'tAddress' is a string containing the transport address formatted
according to the 'tDomain' argument. The ASCII formats for
various values of 'tDomain' are defined by the DISPLAY-HINT for a
TEXTUAL-CONVENTION that represents an address of that type. The
DISPLAY-HINTs used are:
tDomain Source of DISPLAY-HINT [5] [11]
------- ----------------------
transportDomainUdpIpv4 TransportAddressIPv4
transportDomainUdpIpv6 TransportAddressIPv6
transportDomainUdpDns TransportAddressDns
snmpCLNSDomain snmpOSIAddress
snmpCONSDomain snmpOSIAddress
snmpDDPDomain snmpNBPAddress
snmpIPXDomain snmpIPXAddress
rfc1157Domain snmpUDPAddress
Other Use DISPLAY-HINT "1x:"
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'secModel' is the integer value of the SnmpSecurityModel to use
for this operation.
'secName' is a string value representing the SnmpSecurityName to
use for this operation.
'secLevel' is the integer value of the SnmpSecurityLevel to use
for this operation.
An SNMP operation will be sent to the target system by using
security parameters retrieved from a local configuration datastore
based on 'secModel', 'secName', and 'secLevel'. It is the
responsibility of the agent to ensure that sensitive information
in the local configuration datastore is used on behalf of the
correct principals, as identified by the security credentials of
the last entity to modify the pmPolicyAdminStatus for a policy.
To illustrate how this must be configured, consider an example in
which 'joe' installs a policy on 'PMAgent' that will periodically
configure objects on 'TargetAgent' with the credentials of
'Operator'. The following conditions must be true for this policy
to execute with the proper privileges:
- 'Operator's security credentials for TargetAgent must be
installed in PMAgent's local configuration datastore (e.g.,
usmUserTable [6]) indexed by TargetAgent's engineID and
'Operator'.
- VACM [9] must be configured on PMAgent so that 'joe' has access
to the above entry in the appropriate MIB for the local
configuration datastore (e.g., usmUserTable).
- 'joe' must be the last user to modify the pmPolicyAdminStatus
object for the policy.
See the Security Considerations section for more information.
For convenience, constants for 'mPModel', 'secModel', and
'secLevel' are defined in the "Constants" section below.
'contextEngineID' is a string representing the contextEngineID of
the SNMP entity targeted by this operation. It is encoded as a
pair of hex digits (upper- and lowercase are valid) for each octet
of the contextEngineID. If 'tDomain' and 'tAddress' are provided
but 'contextEngineID' is not, then the operation will be directed
to the SNMP entity reachable at 'tDomain' and 'tAddress'.
In order for PolicyScript code to use any of these arguments, all
optional arguments to the left must be included. 'mPModel',
'tDomain', 'tAddress', 'secModel', 'secName', and 'secLevel' must
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be used as a group; if one is specified, they must all be.
'contextEngineID' may only be specified if all others are
specified.
Note that a function that uses NonLocalArgs must provide a
parameter for the contextName that will be required when the
NonLocalArgs are present. Many functions will have the following
logic:
ContextName NonLocalArgs
Supplied Supplied
No No Addressed to default context on
local system.
Yes No Addressed to named context on
local system.
Yes Yes Addressed to named context on
potentially remote system.
No Yes Not allowed.
8.1.2. Form of SNMP Values
Many of the library functions have input or output parameters that
may be one of the many SMI data types. The actual type is not
encoded in the value but is specified elsewhere, possibly by nature
of the situation in which it is used. The exact usage for input and
output is as follows:
Any Integer value
(INTEGER, Integer32, Counter32, Counter64, Gauge32, Unsigned32,
TimeTicks, Counter64):
On input:
An Integer or a String that can be successfully coerced to an
Integer with the ToInteger() operator. It is an RTE if a
string is passed that cannot be converted by ToInteger() into
an integer.
A string of the form
enum_decimal: [ letter | digit | '-' ]* '(' decimal_constant
')'
will also be accepted. In this case the sequence of characters
before the parentheses and the parentheses themselves are
completely ignored, and the decimal_constant inside the
parentheses is converted. Thus, "frame-relay(32)" translates
to the integer 32.
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On output:
An Integer containing the returned value.
Octet String
On input:
Either a String or an Integer. If an Integer, it will be
coerced to a String with the ToString() function. This string
will be used as an unencoded representation of the octet string
value.
On output:
A String containing the unencoded value of the octet string.
Object Identifier
On input and on output:
A String containing a decimal ASCII encoded object identifier
of the following form:
oid: subid [ '.' subid ]* [ '.' ]
subid: '0' | decimal_constant
It is an RTE if an Object Identifier argument is not in the form
above. Note that a trailing '.' is acceptable and will simply be
ignored. (Note, however, that a trailing dot could cause a
strncmp() comparison of two otherwise-identical OIDs to fail;
instead, use oidncmp().)
Note that ASCII descriptors (e.g., "ifIndex") are never used in
these encodings "over the wire". They are never returned from
library functions; nor are they ever accepted by them. NMS user
interfaces are encouraged to allow humans to view object
identifiers with ASCII descriptors, but they must translate those
descriptors to dotted-decimal format before sending them in MIB
objects to policy agents.
Null
On input:
The input is ignored.
On output:
A zero length string.
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8.1.3. Convenience SNMP Functions
8.1.3.1. getVar()
The getVar() function is used to retrieve the value of an SNMP MIB
object instance.
string getVar(string oid [, string contextName, NonLocalArgs])
'oid' is a string containing an ASCII dotted-decimal
representation of an object identifier (e.g.,
"1.3.6.1.2.1.1.1.0").
The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
The optional 'NonLocalArgs' provide addressing and security
information to perform an SNMP operation on a system different
from that of 'this element'.
It is an RTE if the queried object identifier value does not
exist.
This function returns a string containing the returned value,
encoded according to the returned type. Note that no actual
SNMP PDU has to be generated and parsed when the policy MIB
agent resides on the same system as the managed elements.
It is recommended that NMS user interfaces display and allow
input of MIB object names by their descriptor values, followed
by the index in dotted-decimal form (e.g., "ifType.7").
8.1.3.2. exists()
The exists() function is used to verify the existence of an SNMP MIB
object instance.
integer exists(string oid [, string contextName, NonLocalArgs])
'oid' is a string containing an ASCII dotted-decimal
representation of an object identifier (e.g.,
"1.3.6.1.2.1.1.1.0").
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The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
The optional 'NonLocalArgs' provide addressing and security
information to perform an SNMP operation on a system different
from that of 'this element'.
This function returns the value 1 if the SNMP instance exists
and 0 if it doesn't exist. Note that no actual SNMP PDU has to
be generated and parsed when the policy MIB agent resides on
the same system as the managed elements.
It is recommended that NMS user interfaces display and allow
input of MIB object names by their descriptor values, followed
by the index in dotted-decimal form (e.g., "ifType.7").
8.1.3.3. setVar()
The setVar() function is used to set a MIB object instance to a
certain value. The setVar() function is only valid in policyActions.
setVar(string oid, var value, integer type
[, string contextName, NonLocalArgs] )
'oid' is a string containing an ASCII dotted-decimal
representation of an object identifier (e.g.,
"1.3.6.1.2.1.1.1.0").
'value' is a string encoded in the format appropriate to the
'type' parameter. The agent will set the variable specified by
'oid' to the value specified by 'value'.
'type' will be the type of the 'value' parameter and will be
set to one of the values for DataType Constants.
The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero length string, the default context is used.
The optional 'NonLocalArgs' provide addressing and security
information to perform an SNMP operation on a system different
from that of 'this element'. Note that no actual SNMP PDU has
to be generated and parsed when the policy MIB agent resides on
the same system as the managed elements.
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It is an RTE if the set encounters any error.
It is recommended that NMS user interfaces display and allow
input of MIB object names by their descriptor values, followed
by the index in dotted-decimal form (e.g., "ifType.7").
8.1.3.4. searchColumn()
integer searchColumn(string columnoid, string &oid,
string pattern, integer mode
[, string contextName, NonLocalArgs])
searchColumn performs an SNMP walk on a portion of the MIB
searching for objects with values equal to the 'pattern'
parameter.
'columnoid' constrains the search to those variables that share
the same OID prefix (i.e., those that are beneath it in the OID
tree).
A getnext request will be sent requesting the object identifier
'oid'. If 'oid' is an empty string, the value of 'columnoid'
will be sent.
The value returned in each response packet will be transformed
to a string representation of the value of the returned
variable. The string representation of the value will be
formed by putting the value in the form dictated by the "Form
of SNMP Values" rules, and then by performing the ToString()
function on this value, forming 'SearchString'.
The 'mode' value controls what type of match to perform on this
'SearchString' value. There are 6 possibilities for mode:
Mode Search Action
ExactMatch Case sensitive exact match of 'pattern'
and 'SearchString'.
ExactCaseMatch Case insensitive exact match of 'pattern'
and 'SearchString'.
SubstringMatch Case sensitive substring match, finding
'pattern' in 'SearchString'.
SubstringCaseMatch Case insensitive substring match, finding
'pattern' in 'SearchString'.
RegexpMatch Case sensitive regular expression match,
searching 'SearchString' for the regular
expression given in 'pattern'.
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RegexpCaseMatch Case insensitive regular expression match,
searching 'SearchString' for the regular
expression given in 'pattern'.
Constants for the values of 'mode' are defined in the
'Constants' section below.
searchColumn uses the POSIX extended regular expressions
defined in POSIX 1003.2.
The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
The optional 'NonLocalArgs' provide addressing and security
information to perform SNMP operations on a system different
from that of 'this element'.
If a match is found, 'oid' is set to the OID of the matched
value, and 1 is returned. If the search traverses beyond
columnoid or returns an error without finding a match, zero is
returned, and 'oid' isn't modified.
To find the first match, the caller should set 'oid' to the
empty string. To find additional matches, subsequent calls to
searchColumn should have 'oid' set to the OID of the last
match, an operation that searchColumn performs automatically.
For example:
To find an ethernet interface
oid = "";
searchColumn("ifType", oid, "6", 0);
This sends a getnext request for ifType and continues to walk
the tree until a value matching 6 is found or a variable
returns that is not in the 'ifType' subtree.
To find the next ethernet interface, assuming that interface 3
was discovered to be the first:
oid = "ifType.3";
searchColumn("ifType", oid, "6", 0);
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In a loop to determine all the ethernet interfaces, this looks
as follows:
oid = "";
while(searchColumn("ifType", oid, "6", 0)){
/* Do something with oid */
}
Note that in the preceding examples, "ifType" is used as a
notational convenience, and the actual code downloaded to the
policy MIB agent must use the string "1.3.6.1.2.1.2.2.1.3" as
there may be no MIB compiler (or MIB file) available on the
policy MIB agent.
Note that if the value of 'columnoid' is too short and thus
references too much of the object identifier tree (e.g.,
"1.3.6"), 'columnoid' could end up searching a huge number of
variables (if the value was "1.3.6", it would search ALL
variables on the agent). It is the responsibility of the
caller to make sure that 'columnoid' is set appropriately.
8.1.3.5. setRowStatus()
integer setRowStatus(string oid, integer maxTries
[, integer freeOnException , integer seed
, string contextName, NonLocalArgs])
setRowStatus is used to automate the process of finding an
unused row in a read-create table that uses RowStatus whose
index contains an arbitrary integer component for uniqueness.
'oid' is a string containing an ASCII dotted-decimal
representation of an object identifier, with one of the subids
replaced with a '*' character (e.g.,
"1.3.6.1.3.1.99.1.2.1.9.*"). 'oid' must reference an
'instance' of the RowStatus object, and the '*' must replace
any integer index item that may be set to some random value.
setRowStatus will come up with a number for the selected index
item and will attempt to create the instance with the
createAndWait state. If the attempt fails, it will retry with
a different random index value. It will attempt this no more
than 'maxTries' times.
If the optional 'freeOnException' argument is present and equal
to 1, the agent will free this row by setting RowStatus to
'destroy' if, later in the same script invocation, this script
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dies with a run-time exception or by a call to fail(). Note
that this does not apply to exceptions experienced in
subsequent invocations of the script.
If the optional 'seed' argument is present, the initial index
will be set to 'seed'. Otherwise it will be random. 'seed'
may not be present if the 'freeOnException' argument is not
present.
The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
The optional 'NonLocalArgs' provide addressing and security
information to perform an SNMP operation on a system different
from that of 'this element'.
setRowStatus returns the successful integer value for the
index. If it is unsuccessful after 'maxTries', or if zero or
more than one '*' is in OID, -1 will be returned.
The createRow function (below) can also be used when adding
rows to tables. Although createRow has more functionality,
setRowStatus may be preferable in certain situations (for
example, to have the opportunity to inspect default values
created by the agent).
8.1.3.6. createRow()
integer createRow(integer reqPDU, integer reqNumVarbinds,
integer statusColumn, integer maxTries,
integer indexRange,
integer &respPDU, integer &respNumVarbinds,
integer &index
[, integer freeOnException, string contextName,
NonLocalArgs])
createRow is used to automate the process of creating a row in
a read-create table whose index contains an arbitrary integer
component for uniqueness. In particular, it encapsulates the
algorithm behind either the createAndWait or createAndGo
mechanism and the algorithm for finding an unused row in the
table. createRow is not useful for creating rows in tables
whose indexes don't contain an arbitrary integer component.
createRow will perform the operation by sending 'reqPDU' and
returning the results in 'respPDU'. Both 'reqPDU' and
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'respPDU' must previously have been allocated with newPDU.
'reqPDU' and 'respPDU' may both contain the same PDU handle, in
which case the 'reqPDU' is sent and then replaced with the
contents of the received PDU.
'reqNumVarbinds' is an integer greater than zero that specifies
which varbinds in the PDU will be used in this operation. The
first 'reqNumVarbinds' in the PDU are used. Each such varbind
must be of a special form in which the object name must have
one of its subids replaced with a '*' character (e.g.,
"1.3.6.1.3.1.99.1.2.1.9.*"). The subid selected to be replaced
will be an integer index item that may be set to some random
value. The same subid should be selected in each varbind in
the PDU.
'respNumVarbinds' will be modified to contain the number of
varbinds received in the last response PDU.
'statusColumn' identifies which varbind in 'pdu' should be
treated as the RowStatus column, where 0 identifies the 1st
varbind.
createRow will come up with a random integer index value and
will substitute that value in place of the '*' subid in each
varbind. It will then set the value of the RowStatus column to
select the 'createAndGo' mechanism and execute the set. If the
attempt fails due to the unavailability of the 'createAndGo'
mechanism, it will retry with the 'createAndWait' mechanism
selected. If the attempt fails because the chosen index value
is already in use, the operation will be retried with a
different random index value. It will continue to retry
different index values until it succeeds, until it has made
'maxTries' attempts, or until it encounters an error. The
value of 'maxTries' should be chosen to be high enough to
minimize the chance that as the table fills up an attempt to
create a new entry will 'collide' too often and fail.
All random index values must be between 1 and 'indexRange',
inclusive. This is so that values are not attempted for an
index that fall outside of that index's restricted range (e.g.,
1..65535).
If the optional 'freeOnException' argument is present and equal
to 1, the agent will free this row by setting RowStatus to
'destroy' if, later in the same script invocation, this script
dies with a run-time exception or by a call to fail(). Note
that this does not apply to exceptions experienced in
subsequent invocations of the script.
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The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
The optional 'NonLocalArgs' provide addressing and security
information to perform an SNMP operation on a system different
from that of 'this element'.
Note that no actual SNMP PDU has to be generated and parsed
when the policy MIB agent resides on the same system as the
managed elements. If no PDU is generated, the agent must
correctly simulate the behavior of the SNMP Response PDU,
particularly in case of an error.
This function returns zero unless an error occurs, in which
case it returns the proper SNMP Error Constant. If an error
occurred, respPDU will contain the last response PDU as
received from the agent unless no response PDU was received, in
which case respNumVarbinds will be 0. In any event, readError
may be called on the PDU to determine error information for the
transaction.
The 'index' parameter returns the chosen index. If successful,
'index' will be set to the successful integer index. If no
SNMP error occurs but the operation does not succeed due to the
following reasons, 'index' will be set to -1:
1) Unsuccessful after 'maxTries'.
2) An object name had no '*' in it.
3) An object name had more than one '*' in it.
For example, createRow() might be used as follows:
var index, pdu = newPDU(), nVars = 0;
writeVar(pdu, nVars++, "hlHostControlDataSource.*",
"ifIndex." + ev(0), Oid);
writeVar(pdu, nVars++, "hlHostControlNlMaxDesiredEntries.*",
1000, Integer);
writeVar(pdu, nVars++, "hlHostControlAlMaxDesiredEntries.*",
1000, Integer);
writeVar(pdu, nVars++, "hlHostControlOwner.*", "policy",
String);
writeVar(pdu, nVars++, "hlHostControlStatus.*", "active(1)",
Integer);
if (createRow(pdu, nVars, 4, 20, 65535,
pdu, nVars, index) != 0
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|| index == -1)
return;
// index now contains index of new row
8.1.3.7. counterRate()
When a policy wishes to make a decision based on the rate of a
counter, it faces a couple of problems:
1. It may have to run every X minutes but have to make decisions on
rates calculated over at least Y minutes, where Y > X. This would
require the complexity of managing a queue of old counter values.
2. The policy script has no control over exactly when it will run.
The counterRate() function is designed to surmount these problems
easily.
integer counterRate(string oid, integer minInterval
[, integer 64bit,
string discOid, integer discMethod,
string contextName, NonLocalArgs])
'counterRate' retrieves the variable specified by oid once per
invocation. It keeps track of timestamped values retrieved on
previous invocations by this execution context so that it can
calculate a rate over a period longer than that since the last
invocation.
'oid' is the object identifier of the counter value that will
be retrieved. The most recent previously saved value of the
same object identifier that is at least 'minInterval' seconds
old will be subtracted from the newly retrieved value, yielding
a delta. If 'minInterval' is zero, this delta will be
returned. Otherwise, this delta will be divided by the number
of seconds elapsed between the two retrievals, and the
integer-valued result will be returned (rounding down when
necessary).
If there was no previously saved retrieval older than
'minInterval' seconds, then -1 will be returned. It is an RTE
if the query returns noSuchName, noSuchInstance, or
noSuchObject or an object that is not of type Counter32 or
Counter64.
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The delta calculation will allow for 32-bit counter semantics
if it encounters rollover between the two retrievals, unless
the optional argument '64bit' is present and equal to 1, in
which case it will allow for 64-bit counter semantics.
'discOid' and 'discMethod' may only be present together.
'discOid' contains an object identifier of a discontinuity
indicator value that will be retrieved simultaneously with each
counter value:
1. If 'discMethod' is equal to 1 and the discontinuity
indicator is less than the last one retrieved, then a
discontinuity is indicated.
2. If 'discMethod' is equal to 2 and the discontinuity
indicated is different from the last one retrieved, then
a discontinuity is indicated.
If this value indicates a discontinuity, this counter value
(and its timestamp) will be stored, but all previously stored
counter values will be invalidated and -1 will be returned.
The implementation will have to store a number of timestamped
counter values. The implementation must keep all values that
are newer than minInterval seconds, plus the newest value that
is older than minInterval seconds. Other than this one value
that is older than minInterval seconds, the implementation
should discard any older values.
For example:
Policy that executes every 60 seconds:
rate = counterRate("ifInOctets.$*", 300);
if (rate > 1000000)
...
Another example, with a discontinuity indicator:
Policy that executes every 60 seconds:
rate = counterRate("ifInOctets.$*", 300, 0,
"sysUpTime.0", 1);
if (rate > 1000000)
...
Another example, with zero minInterval:
Policy that executes every 60 seconds:
delta = counterRate("ifInErrors.$*", 0);
if (delta > 100)
...
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The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
8.1.4. General SNMP Functions
It is desirable that a general SNMP interface have the ability to
perform SNMP operations on multiple variables at once and that it
allow multiple varbind lists to exist at once. The newPdu, readVar,
and writeVar functions exist to provide these facilities in a
language without pointers, arrays, and memory allocators.
newPDU is called to allocate a PDU and return an integer handle to
it. As PDUs are automatically freed when the script exits and can be
reused during execution, there is no freePDU().
readVar and writeVar access a variable length varbind list for a PDU.
The PDU handle and the index of the variable within that PDU are
specified in every readVar and writeVar operation. Once a PDU has
been fully specified by one or more calls to writeVar, it is passed
to snmpSend (by referencing the PDU handle) and the number of
varbinds to be included in the operation. When a response is
returned, the contents of the response are returned in another PDU
and may be read by one or more calls to readVar. Error information
may be read from the PDU with the readError function. Because
GetBulk PDUs send additional information in the SNMP header, the
writeBulkParameters function is provided to configure these
parameters.
Varbinds in this data store are created automatically whenever they
are written by any writeVar or snmpSend operation.
For example:
var pdu = newPDU();
var nVars = 0, oid, type, value;
writeVar(pdu, nVars++, "sysDescr.0", "", Null);
writeVar(pdu, nVars++, "sysOID.0", "", Null);
writeVar(pdu, nVars++, "ifNumber.0", "", Null);
if (snmpSend(pdu, nVars, Get, pdu, nVars))
return;
readVar(pdu, 0, oid, value, type);
readVar(pdu, 1, oid, value, type);
readVar(pdu, 2, oid, value, type);
...
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or,
var pdu = newPDU();
var nVars = 0, oid1, oid2;
writeVar(pdu, nVars++, "ifIndex", "", Null);
writeVar(pdu, nVars++, "ifType", "", Null);
while(!done){
if (snmpSend(pdu, nVars, Getnext, pdu, nVars))
continue;
readVar(pdu, 0, oid1, value, type);
readVar(pdu, 1, oid2, value, type);
/* leave OIDs alone, now PDU #0 is set up for next step
in table walk. */
if (oidncmp(oid1, "ifIndex", oidlen("ifIndex")))
done = 0;
...
}
Note that in the preceding examples, descriptors such as ifType and
sysDescr are used in object identifiers solely as a notational
convenience. The actual code downloaded to the policy MIB agent must
use a dotted decimal notation only, as there may be no MIB compiler
(or MIB file) available on the policy MIB agent.
To conform to this specification, implementations must allow each
policy script invocation to allocate at least 5 PDUs with at least 64
varbinds per list. It is suggested that implementations limit the
total number of PDUs per invocation to protect other script
invocations from a malfunctioning script (e.g., a script that calls
newPDU() in a loop).
8.1.4.1. newPDU()
integer newPDU()
newPDU will allocate a new PDU and return a handle to the PDU.
If no PDU could be allocated, -1 will be returned. The PDU's
initial values of nonRepeaters and maxRepetitions will be zero.
8.1.4.2. writeVar()
writeVar(integer pdu, integer varBindIndex,
string oid, var value, integer type)
writeVar will store 'oid', 'value', and 'type' in the specified
varbind.
'pdu' is the handle to a PDU allocated by newPDU().
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'varBindIndex' is a non-negative integer that identifies the
varbind within the specified PDU modified by this call. The
first varbind is number 0.
'oid' is a string containing an ASCII dotted-decimal
representation of an object identifier (e.g.,
"1.3.6.1.2.1.1.1.0").
'value' is the value to be stored, of a type appropriate to the
'type' parameter.
'type' will be the type of the value parameter and will be set
to one of the values for DataType Constants.
It is an RTE if any of the parameters don't conform to the
rules above.
8.1.4.3. readVar()
readVar(integer pdu, integer varBindIndex, string &oid,
var &value, integer &type)
readVar will retrieve the oid, the value, and its type from the
specified varbind.
'pdu' is the handle to a PDU allocated by newPDU().
'varBindIndex' is a non-negative integer that identifies the
varbind within the specified PDU read by this call. The first
varbind is number 0.
The object identifier value of the referenced varbind will be
copied into the 'oid' parameter, formatted in an ASCII dotted-
decimal representation (e.g., "1.3.6.1.2.1.1.1.0").
'value' is the value retrieved, of a type appropriate to the
'type' parameter.
'type' is the type of the value parameter and will be set to
one of the values for DataType Constants.
It is an RTE if 'pdu' doesn't reference a valid PDU or
'varBindIndex' doesn't reference a valid varbind.
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8.1.4.4. snmpSend()
integer snmpSend(integer reqPDU, integer reqNumVarbinds,
integer opcode,
integer &respPDU, integer &respNumVarbinds,
[, string contextName , NonLocalArgs] )
snmpSend will perform an SNMP operation by sending 'reqPDU' and
returning the results in 'respPDU'. Both 'reqPDU' and
'respPDU' must previously have been allocated with newPDU.
'reqPDU' and 'respPDU' may both contain the same PDU handle, in
which case the 'reqPDU' is sent and then replaced with the
contents of the received PDU. If the opcode specifies a Trap
or V2trap, 'respPDU' will not be modified.
'reqNumVarbinds' is an integer greater than zero that specifies
which varbinds in the PDU will be used in this operation. The
first 'reqNumVarbinds' in the PDU are used. 'respNumVarbinds'
will be modified to contain the number of varbinds received in
the response PDU, which, in the case of GetBulk or an error,
may be substantially different from reqNumVarbinds.
'opcode' is the type of SNMP operation to perform and must be
one of the values for SNMP Operation Constants listed in the
'Constants' section below.
The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
Note that no actual SNMP PDU has to be generated and parsed
when the policy MIB agent resides on the same system as the
managed elements. If no PDU is generated, the agent must
correctly simulate the behavior of the SNMP Response PDU,
particularly in case of an error.
This function returns zero unless an error occurs, in which
case it returns the proper SNMP Error Constant. If an error
occurred, respPDU will contain the response PDU as received
from the agent, unless no response PDU was received, in which
case respNumVarbinds will be 0. In any event, readError may be
called on the PDU to determine error information for the
transaction.
If an SNMP Version 1 trap is requested (the opcode is Trap(4)),
then SNMP Version 2 trap parameters are supplied and converted
according to the rules of RFC 3584 [8], section 3.2. The first
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variable binding must be sysUpTime.0, and the second must be
snmpTrapOID.0, as per RFC 3416 [7], section 4.2.6. Subsequent
variable bindings are copied to the SNMP Version 1 trap PDU in
the usual fashion.
8.1.4.5. readError()
readError(integer pdu, integer numVarbinds, integer &errorStatus,
integer &errorIndex, integer &hasException)
Returns the error information in a PDU.
'errorStatus' contains the error-status field from the response
PDU or a local error constant if the error was generated
locally. If no error was experienced or no PDU was ever copied
into this PDU, this value will be 0.
'errorIndex' contains the error-index field from the response
PDU. If no PDU was ever copied into this PDU, this value will
be 0.
'hasException' will be 1 if any of the first 'numVarbinds'
varbinds in the PDU contain an exception (Nosuchobject,
Nosuchinstance, Endofmibview); otherwise it will be 0.
It is an RTE if 'pdu' does not reference a valid PDU or if
'numVarbinds' references varbinds that aren't valid.
8.1.4.6. writeBulkParameters()
writeBulkParameters(integer pdu, integer nonRepeaters,
integer maxRepetitions)
Modifies the parameters in a PDU in any subsequent GetBulk
operation sent by the PDU. 'nonRepeaters' will be copied into
the PDU's non-repeaters field, and 'maxRepetitions' into the
max-repetitions field.
This function may be called before or after writeVar is called
to add varbinds to the PDU, but it must be called before the
PDU is sent; otherwise, it will have no effect. A new PDU is
initialized with nonRepeaters set to zero and maxRepetitions
set to zero. If a Bulk PDU is sent before writeBulkParameters
is called, these default values will be used. If
writeBulkParameters is called to modify a PDU, it is acceptable
if this PDU is later sent as a type other than bulk. The
writeBulkParameters call will only affect subsequent sends of
Bulk PDUs. If a PDU is used to receive the contents of a
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response, the values of nonRepeaters and maxRepetitions are
never modified.
8.1.5. Constants for SNMP Library Functions
The following constants are defined for use with all SNMP Library
Functions. Policy code will be executed in an environment where the
following constants are declared. (Note that the constant
declarations below will not be visible in the policyCondition or
policyAction code.) These constants are reserved words and cannot be
used for any variable or function name.
Although these declarations are expressed here as C 'const's, the
'const' construct itself is not available to be used in policy code.
// Datatype Constants
// From RFC 2578 [2]
const integer Integer = 2;
const integer Integer32 = 2;
const integer String = 4;
const integer Bits = 4;
const integer Null = 5;
const integer Oid = 6;
const integer IpAddress = 64;
const integer Counter32 = 65;
const integer Gauge32 = 66;
const integer Unsigned32 = 66;
const integer TimeTicks = 67;
const integer Opaque = 68;
const integer Counter64 = 70;
// SNMP Exceptions from RFC 3416 [7]
const integer NoSuchObject = 128;
const integer NoSuchInstance = 129;
const integer EndOfMibView = 130;
// SNMP Error Constants from RFC 3416 [7]
const integer NoError = 0;
const integer TooBig = 1;
const integer NoSuchName = 2;
const integer BadValue = 3;
const integer ReadOnly = 4;
const integer GenErr = 5;
const integer NoAccess = 6;
const integer WrongType = 7;
const integer WrongLength = 8;
const integer WrongEncoding = 9;
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const integer WrongValue = 10;
const integer NoCreation = 11;
const integer InconsistentValue = 12;
const integer ResourceUnavailable = 13;
const integer CommitFailed = 14;
const integer UndoFailed = 15;
const integer AuthorizationError = 16;
const integer NotWritable = 17;
const integer InconsistentName = 18;
// "Local" Errors
// These are also possible choices for errorStatus returns
// For example: unknown PDU, maxVarbinds is bigger than number
// written with writeVar, unknown opcode, etc.
const integer BadParameter = 1000;
// Request would have created a PDU larger than local limitations
const integer TooLong = 1001;
// A response to the request was received but errors were encountered
// when parsing it.
const integer ParseError = 1002;
// Local system has complained of an authentication failure
const integer AuthFailure = 1003;
// No valid response was received in a timely fashion
const integer TimedOut = 1004;
// General local failure including lack of resources
const integer GeneralFailure = 1005;
// SNMP Operation Constants from RFC 3416 [7]
const integer Get = 0;
const integer Getnext = 1;
const integer Set = 3;
const integer Trap = 4;
const integer Getbulk = 5;
const integer Inform = 6;
const integer V2trap = 7;
// Constants from RFC 3411 [1] for SnmpMessageProcessingModel
const integer SNMPv1 = 0;
const integer SNMPv2c = 1;
const integer SNMPv3 = 3;
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// Constants from RFC 3411 [1] for SnmpSecurityModel
const integer SNMPv1 = 1;
const integer SNMPv2c = 2;
const integer USM = 3;
// SnmpSecurityLevel Constants from RFC 3411 [1]
const integer NoAuthNoPriv = 1;
const integer AuthNoPriv = 2;
const integer AuthPriv = 3;
// Constants for use with searchColumn
const integer ExactMatch = 0;
const integer ExactCaseMatch = 1;
const integer SubstringMatch = 2;
const integer SubstringCaseMatch = 3;
const integer RegexpMatch = 4;
const integer RegexpCaseMatch = 5;
8.2. Policy Library Functions
Policy Library Functions provide access to information specifically
related to the execution of policies.
8.2.1. elementName()
The elementName() function is used to determine what the current
element is and can be used to provide information about the type of
element and how it is indexed.
string elementName()
elementName returns a string containing an ASCII dotted-decimal
representation of an object identifier (e.g.,
1.3.6.1.2.1.1.1.0). This object identifier identifies an
instance of a MIB object that is an attribute of 'this
element'.
8.2.2. elementAddress()
elementAddress(&tDomain, &tAddress)
elementAddress finds a domain/address pair that can be used to
access 'this element' and returns the values in 'tDomain' and
'tAddress'.
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8.2.3. elementContext()
string elementContext()
elementContext() returns a string containing the SNMP
contextName of 'this element'.
8.2.4. ec()
The ec() (element count) and ev() (element value) functions provide
convenient access to the components of the index for 'this element'.
Typical uses will be in creating the index to other, related
elements.
integer ec()
ec() returns an integer count of the number of index
subidentifiers that exist in the index for 'this element'.
8.2.5. ev()
integer ev(integer n)
ev() returns the value of the nth subidentifier in the index
for 'this element'. The first subidentifier is indexed at 0.
It is an RTE if n specifies a subidentifier beyond the last
subidentifier.
8.2.6. roleMatch()
The roleMatch() function is used to check whether an element has been
assigned a particular role.
integer roleMatch(string roleString [, string element,
string contextName, string contextEngineID])
'roleString' is a string. The optional argument 'element'
contains the OID name of an element, defaulting to the current
element if 'element' is not supplied. If roleString exactly
matches (content and length) any role assigned to the specified
element, the function returns 1. If no roles match, the
function returns 0.
The optional 'contextName' argument contains the SNMP context
on which to operate. If 'contextName' is not present, the
contextName of 'this element' will be used. If 'contextName'
is the zero-length string, the default context is used.
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'contextEngineID' contains the contextEngineID of the remote
system on which 'element' resides. It is encoded as a pair of
hex digits (upper- and lowercase are valid) for each octet of
the contextEngineID. If 'contextEngineID' is not present, the
contextEngineID of 'this element' will be used.
'contextEngineID' may only be present if the 'element' and
'context' arguments are present.
8.2.7. Scratchpad Functions
Every maxLatency time period, every policy runs once for each
element. When the setScratchpad function executes, it stores a value
named by a string that can be retrieved with getScratchpad() even
after this policy execution code exits. This allows sharing of data
between a condition and an action, two conditions executing on
different elements, or even different policies altogether.
The value of 'scope' controls which policy/element combinations can
retrieve this 'varName'/'value' pair. The following are options for
'scope':
Global
The 'varName'/'value' combination will be available in the
condition or action of any policy while it is executing on any
element. Note that any information placed here will be visible
to all other scripts on this system regardless of their
authority. Sensitive information should not be placed in
global scratchpad variables.
Policy
The 'varName'/'value' combination will be available in any
future execution of the condition or action of the current
policy (regardless of what element the policy is executing on).
If a policy is ever deleted, or if its condition or action code
is modified, all values in its 'Policy' scope will be deleted.
PolicyElement
The 'varName'/'value' combination will be available in future
executions of the condition or action of the current policy,
but only when the policy is executing on the current element.
If a policy is ever deleted, or if its condition or action code
is modified, all values in its 'PolicyElement' scope will be
deleted. The agent may also periodically delete values in a
'PolicyElement' scope if the corresponding element does not
exist (in other words, if an element disappears for a period
and reappears, values in its 'PolicyElement' scope may or may
not be deleted).
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setScratchpad's 'storageType' argument allows the script to control
the lifetime of a variable stored in the scratchpad. If the
storageType is equal to the constant 'volatile', then this variable
must be deleted on a reboot. If it is equal to 'nonVolatile', then
this variable should be stored in non-volatile storage, where it will
be available after a reboot. If the 'storageType' argument is not
present, the variable will be volatile and will be erased on reboot.
If the optional 'freeOnException' argument is present and equal to 1,
the agent will free this variable if, later in the same script
invocation, this script dies with a run-time exception or by a call
to fail(). (Note that this does not apply to exceptions experienced
in subsequent invocations of the script.)
Note that there may be implementation-specific limits on the number
of scratchpad variables that can be allocated. The limit of unique
scratchpad variables may be different for each scope or storageType.
It is suggested that implementations limit the total number of
scratchpad variables per script to protect other scripts from a
malfunctioning script. In addition, compliant implementations must
support at least 50 Global variables, 5 Policy variables per policy,
and 5 PolicyElement variables per policy-element pair.
Scratchpad Usage Examples
Policy Element Action
A ifIndex.1 setScratchpad(Global, "foo", "55")
A ifIndex.1 getScratchpad(Global, "foo", val) --> 55
A ifIndex.2 getScratchpad(Global, "foo", val) --> 55
B ifIndex.2 getScratchpad(Global, "foo", val) --> 55
B ifIndex.2 setScratchpad(Global, "foo", "16")
A ifIndex.1 getScratchpad(Global, "foo", val) --> 16
Policy Element Action
A ifIndex.1 setScratchpad(Policy, "bar", "75")
A ifIndex.1 getScratchpad(Policy, "bar", val) --> 75
A ifIndex.2 getScratchpad(Policy, "bar", val) --> 75
B ifIndex.1 getScratchpad(Policy, "bar", val) not found
B ifIndex.1 setScratchpad(Policy, "bar", "20")
A ifIndex.2 getScratchpad(Policy, "bar", val) --> 75
B ifIndex.2 getScratchpad(Policy, "bar", val) --> 20
Policy Element Action
A ifIndex.1 setScratchpad(PolicyElement, "baz", "43")
A ifIndex.1 getScratchpad(PolicyElement, "baz", val) --> 43
A ifIndex.2 getScratchpad(PolicyElement, "baz", val) not found
B ifIndex.1 getScratchpad(PolicyElement, "baz", val) not found
A ifIndex.2 setScratchpad(PolicyElement, "baz", "54")
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B ifIndex.1 setScratchpad(PolicyElement, "baz", "65")
A ifIndex.1 getScratchpad(PolicyElement, "baz", val) --> 43
A ifIndex.2 getScratchpad(PolicyElement, "baz", val) --> 54
B ifIndex.1 getScratchpad(PolicyElement, "baz", val) --> 65
Policy Element Action
A ifIndex.1 setScratchpad(PolicyElement, "foo", "11")
A ifIndex.1 setScratchpad(Global, "foo", "22")
A ifIndex.1 getScratchpad(PolicyElement, "foo", val) --> 11
A ifIndex.1 getScratchpad(Global, "foo", val) --> 22
Constants
The following constants are defined for use with the scratchpad
functions. Policy code will be executed in an environment where the
following constants are declared. (Note that these constant
declarations will not be visible in the policyCondition or
policyAction MIB objects.)
Although these declarations are expressed here as C 'const's, the
'const' construct itself is not available to be used inside of policy
code.
// Scratchpad Constants
// Values of scope
const integer Global = 0;
const integer Policy = 1;
const integer PolicyElement = 2;
// Values of storageType
const integer Volatile = 0;
const integer NonVolatile = 1;
8.2.8. setScratchpad()
setScratchpad(integer scope, string varName [, string value,
integer storageType, integer freeOnException ])
The setScratchpad function stores a value that can be retrieved
even after this policy execution code exits.
The value of 'scope' controls which policy/element combinations
can retrieve this 'varName'/'value' pair. The options for
'scope' are Global, Policy, and PolicyElement.
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'varName' is a string used to identify the value. Subsequent
retrievals of the same 'varName' in the proper scope will
return the value stored. Note that the namespace for 'varName'
is distinct for each scope. 'varName' is case sensitive.
'value' is a string containing the value to be stored.
ToString(value) is called on 'value' to convert it to a string
before storage.
If the 'value' argument is missing, the 'varName' in scope
'scope' will be deleted if it exists.
If the optional 'storageType' argument is present and is equal
to the constant 'Volatile', then this variable must be deleted
on a reboot. If it is equal to 'NonVolatile', then this
variable should be stored in non-volatile storage, where it
will be available after a reboot. If the 'storageType'
argument is not present, the variable will be volatile and will
be erased on reboot. 'storageType' may not be present if the
'value' argument is not present. If the variable already
existed, its previous storageType is updated according to the
current 'storageType' argument.
If the optional 'freeOnException' argument is present and equal
to 1, the agent will free this variable if, later in the same
script invocation, this script dies with a run-time exception
or by a call to fail(). (Note that this does not apply to
exceptions experienced in subsequent invocations of the
script.)
8.2.9. getScratchpad()
integer getScratchpad(integer scope, string varName,
string &value)
The getScratchpad function allows the retrieval of values that
were stored previously in this execution context or in other
execution contexts. The value of 'scope' controls which
execution contexts can pass a value to this execution context.
The options for 'scope' are Global, Policy, and PolicyElement.
'varName' is a string used to identify the value. Subsequent
retrievals of the same 'varName' in the proper scope will
return the value stored. Note that the namespace for varName
is distinct for each scope. As a result, getScratchpad cannot
force access to a variable in an inaccessible scope; it can
only retrieve variables by referencing the proper scope in
which they were set. 'varName' is case sensitive.
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On successful return, 'value' will be set to the value that was
previously stored; otherwise, 'value' will not be modified.
This function returns 1 if a value was previously stored and 0
otherwise.
8.2.10. signalError()
The signalError() function is used by the script to indicate to a
management station that it is experiencing abnormal behavior.
signalError() turns on the conditionUserSignal(3) or
actionUserSignal(5) bit in the associated pmTrackingPEInfo object
(subsequent calls to signalError() have no additional effect). This
bit is initially cleared at the beginning of each execution. If,
upon a subsequent execution, the script finishes without calling
signalError, the bit will be cleared.
signalError()
The signalException function takes no arguments and returns no
value.
8.2.11. defer()
Precedence groups enforce the rule that for each element, of the
ready policies that match the condition, only the one with the
highest precedence value will be active. Unfortunately, once the
winning policy has been selected and the action begins running,
situations can occur in which the policy script determines that it
cannot complete its task. In many such cases, it is desirable that
the next runner-up ready policy be executed. In the previous
example, it would be desirable that at least bronze behavior be
configured if gold is appropriate but gold isn't possible.
When a policy defers, it exits, and the ready, condition-matching
policy with the next-highest precedence is immediately run. Because
this might also defer, the execution environment must remember where
it is in the precedence chain so that it can continue going down the
chain until an action completes without deferring, or until no
policies are left in the precedence group. Once a policy finishes
successfully, the next iteration will begin at the top of the
precedence chain.
There are two ways to defer. A script can exit by calling fail() and
specify that it should defer immediately. Alternately, a script can
instruct the execution environment to defer automatically in the
event of a run-time exception.
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defer(integer deferOnRTE)
The defer function changes the run-time exception behavior of a
script. By default, a script will not defer when it encounters
an RTE. If defer(1) is called, the exit behavior is changed so
that the script will defer when it is terminated due to an RTE.
If defer(0) is called, the script is reset to its default
behavior and will not defer.
Note that calling defer doesn't cause the script to exit.
Defer only changes the default behavior if an RTE occurs later
in this invocation.
8.2.12. fail()
fail(integer defer, integer free [, string message] )
The fail function causes the script to optionally perform
certain functions and then exit.
If 'defer' is 1, this script will defer to the next lower
precedence ready policy in the same precedence group whose
condition matches. If 'defer' isn't 1, it will not defer.
Note that if a condition defers, it is functionally equivalent
to the condition returning false.
If 'free' is 1, certain registered resources will be freed.
If, earlier in this script invocation, any rows were created by
createRow with the 'freeOnException' option, the execution
environment will set the RowStatus of each row to 'destroy' to
delete the row. Further, if earlier in this script invocation
any scratchpad variables were created or modified with the
'freeOnException' option, they will be deleted.
If the optional 'message' argument is present, it will be
logged to the debugging table if pmPolicyDebugging is turned on
for this policy.
This function does not return. Instead, the script will
terminate.
8.2.13. getParameters()
From time to time, policy scripts may be parameterized so that they
are supplied with one or more parameters (e.g., site-specific
constants). These parameters may be installed in the
pmPolicyParameters object and are accessible to the script via the
getParameters() function. If it is necessary for multiple parameters
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to be passed to the script, the script can choose whatever
encoding/delimiting mechanism is most appropriate so that the
multiple parameters can be stored in the associated instance of
pmPolicyParameters.
string getParameters()
The getParameters function takes no arguments. It returns a
string containing the value of the pmPolicyParameters object
for the running policy.
For example, if a policy is to apply to "slow speed interfaces" and
the cutoff point for slow speed should be parameterized, the policy
filter should be:
getVar("ifSpeed.$*") == getParameters()
In this example, one can store the string "128000" in the policy's
pmPolicyParameters object to cause this policy to act on all 128 Kbps
interfaces.
8.3. Utility Library Functions
Utility Library Functions are provided to enable more efficient
policy scripts.
8.3.1. regexp()
integer regexp(string pattern, string str,
integer case [, string &match])
regexp searches 'str' for matches to the regular expression
given in `pattern`. regexp uses the POSIX extended regular
expressions defined in POSIX 1003.2.
If `case` is 0, the search will be case insensitive; otherwise,
it will be case sensitive.
If a match is found, 1 is returned, otherwise 0 is returned.
If the optional argument 'match' is provided and a match is
found, 'match' will be replaced with the text of the first
substring of 'str' that matches 'pattern'. If no match is
found, it will be unchanged.
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8.3.2. regexpReplace()
string regexpReplace(string pattern, string replacement,
string str, integer case)
regexpReplace searches 'str' for matches to the regular
expression given in 'pattern', replacing each occurrence of
matched text with 'replacement'. regexpReplace uses the POSIX
extended regular expressions defined in POSIX 1003.2.
If `case` is 0, the search will be case insensitive; otherwise,
it will be case sensitive.
The modified string is returned (it would be the same as the
original string if no matches were found).
8.3.3. oidlen()
integer oidlen(string oid)
oidlen returns the number of subidentifiers in 'oid'. 'oid' is
a string containing an ASCII dotted-decimal representation of
an object identifier (e.g., "1.3.6.1.2.1.1.1.0").
8.3.4. oidncmp()
integer oidncmp(string oid1, string oid2, integer n)
Arguments 'oid1' and 'oid2' are strings containing ASCII
dotted-decimal representations of object identifiers (e.g.,
"1.3.6.1.2.1.1.1.0").
oidcmp compares not more than n subidentifiers of 'oid1' and
'oid2' and returns -1 if 'oid1' is less than 'oid2', 0 if they
are equal, and 1 if 'oid1' is greater than 'oid2'.
8.3.5. inSubtree()
integer inSubtree(string oid, string prefix)
Arguments 'oid' and 'prefix' are strings containing ASCII
dotted-decimal representations of object identifiers (e.g.,
"1.3.6.1.2.1.1.1.0").
inSubtree returns 1 if every subidentifier in 'prefix' equals
the corresponding subidentifier in 'oid', otherwise it returns
0. The is equivalent to oidncmp(oid1, prefix, oidlen(prefix))
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is provided because this is an idiom and because it avoids
evaluating 'prefix' twice if it is an expression.
8.3.6. subid()
integer subid(string oid, integer n)
subid returns the value of the nth (starting at zero)
subidentifier of 'oid'. 'oid' is a string containing an ASCII
dotted-decimal representation of an object identifier (e.g.,
"1.3.6.1.2.1.1.1.0").
If n specifies a subidentifier beyond the length of 'oid', a
value of -1 is returned.
8.3.7. subidWrite()
integer subidWrite(string oid, integer n, integer subid)
subidWrite sets the value of the nth (starting at zero)
subidentifier of 'oid' to 'subid'. 'oid' is a string
containing an ASCII dotted-decimal representation of an object
identifier (e.g., "1.3.6.1.2.1.1.1.0").
If n specifies a subidentifier beyond the length of 'oid', a
value of -1 is returned. Note that appending subidentifiers
can be accomplished with the string concatenation '+' operator.
If no error occurs, zero is returned.
8.3.8. oidSplice()
string oidSplice(string oid1, integer offset, integer len, string
oid2)
oidSplice returns an OID formed by replacing 'len'
subidentifiers in 'oid1' with all of the subidentifiers from
'oid2', starting at 'offset' in 'oid1' (the first subidentifier
is at offset 0). The OID length will be extended, if
necessary, if 'offset' + 'len' extends beyond the end of
'oid1'. If 'offset' is larger than the length of oid1, then an
RTE will occur.
The resulting OID is returned.
For example:
oidSplice("1.3.6.1.2.1", 5, 1, "7") => "1.3.6.1.2.7"
oidSplice("1.3.6.1.2.1", 4, 2, "7.7") => "1.3.6.1.7.7"
oidSplice("1.3.6.1.2.1", 4, 3, "7.7.7") => "1.3.6.1.7.7.7"
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8.3.9. parseIndex()
ParseIndex is provided to make it easy to pull index values from OIDs
into variables.
var parseIndex(string oid, integer &index, integer type,
integer len)
parseIndex pulls values from the instance identification
portion of 'oid', encoded as per Section 7.7, "Mapping of the
INDEX Clause", of the SMIv2 [2].
'oid' is the OID to be parsed.
'index' describes which subid to begin parsing at. 'index'
will be modified to indicate the subid after the last one
parsed (even if this points past the last subid). The first
subid is index 0. If any error occurs, 'index' will be set to
-1 on return. If the input index is less than 0 or refers past
the end of the OID, 'index' will be set to -1 on return and the
function will return 0.
If 'type' is Integer, 'len' will not be consulted. The return
value is the integer value of the next subid.
If 'type' is String and 'len' is greater than zero, 'len'
subids will be parsed. For each subid parsed, the chr() value
of the subid will be appended to the returned string. If any
subid is greater than 255, 'index' will be set to -1 on return,
and an empty string will be returned. If there are fewer than
'len' subids left in 'oid', 'index' will be set to -1 on
return, but a string will be returned containing a character
for each subid that was left.
If 'type' is String and 'len' is zero, the next subid will be
parsed to find N, the length of the string. Then, that many
subids will be parsed. For each subid parsed, the chr() value
of the subid will be appended to the returned string. If any
subid is greater than 255, 'index' will be set to -1 on return,
and an empty string will be returned. If there are fewer than
N subids left in 'oid', 'index' will be set to -1 on return,
but a string will be returned containing a character for each
subid that was left.
If 'type' is String and 'len' is -1, subids will be parsed
until the end of 'oid'. For each subid parsed, the chr() value
of the subid will be appended to the returned string. If any
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subid is greater than 255, 'index' will be set to -1 on return,
and an empty string will be returned.
If 'type' is Oid and 'len' is greater than zero, 'len' subids
will be parsed. For each subid parsed, the decimal-encoded
value of the subid will be appended to the returned string,
with a '.' character appended between each output subid, but
not after the last subid. If there are fewer than 'len' subids
left in 'oid', 'index' will be set to -1 on return, but a
string will be returned containing an encoding for each subid
that was left.
If 'type' is Oid and 'len' is zero, the next subid will be
parsed to find N, the number of subids to parse. For each
subid parsed, the decimal-encoded value of the subid will be
appended to the returned string, with a '.' character appended
between each output subid but not after the last subid. If
there are fewer than N subids left in 'oid', 'index' will be
set to -1 on return, but a string will be returned containing
an encoding for each subid that was left.
If 'type' is Oid and 'len' is -1, subids will be parsed until
the end of 'oid'. For each subid parsed, the decimal-encoded
value of the subid will be appended to the returned string,
with a '.' character appended between each output subid, but
not after the last subid.
For example, to decode the index component of an instance of the
ipForward table:
oid = "ipForwardIfIndex.0.0.0.0.13.0.192.168.1.1";
index = 11;
dest = parseIndex(oid, index, String, 4);
proto = parseIndex(oid, index, Integer, 0);
policy = parseIndex(oid, index, Integer, 0);
nextHop = parseIndex(oid, index, String, 4);
// proto and policy now contain integer values
// dest and nextHop now contain 4 byte IP addresses. Use
// stringToDotted to get them to dotted decimal notation:
// e.g.: stringToDotted(nextHop) => "192.168.1.1"
8.3.10. stringToDotted()
stringToDotted() is provided to encode strings suitable for the index
portion of an OID or to convert the binary encoding of an IP address
to a dotted-decimal encoding.
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string stringToDotted(string value)
If 'value' is the zero-length string, the zero-length string is
returned.
The decimal encoding of the first byte of 'value' is appended
to the output string. Then, for each additional byte in
'value', a '.' is appended to the output string, followed by
the decimal encoding of the additional byte.
8.3.11. integer()
integer integer(var input)
integer converts 'input' into an integer by using the rules
specified for ToInteger(), returning the integer-typed results.
8.3.12. string()
string string(var input)
string converts 'input' into a string by using the rules
specified for ToString(), returning the string-typed results.
8.3.13. type()
string type(var variable)
type returns the type of its argument as either the string
'String' or the string 'Integer'.
8.3.14. chr()
string chr(integer char)
Returns a one-character string containing the character
specified by the ASCII code contained in 'char'.
8.3.15. ord()
integer ord(string str)
Returns the ASCII value of the first character of 'str'. This
function complements chr().
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8.3.16. substr()
string substr(string &str, integer offset
[, integer len, string replacement])
Extracts a substring out of 'str' and returns it. The first
octet is at offset 0. If the offset is negative, the returned
string starts that far from the end of 'str'. If 'len' is
positive, the returned string contains up to 'len' octets, up
to the end of the string. If 'len' is omitted, the returned
string includes everything to the end of 'str'. If 'len' is
negative, abs(len) octets are left off the end of the string.
If a substring is specified that is partly outside the string,
the part within the string is returned. If the substring is
totally outside the string, a zero-length string is produced.
If the optional 'replacement' argument is included, 'str' is
modified. 'offset' and 'len' act as above to select a range of
octets in 'str'. These octets are replaced with octets from
'replacement'. If the replacement string is shorter or longer
than the number of octets selected, 'str' will shrink or grow,
respectively. If 'replacement' is included, the 'len' argument
must also be included.
Note that to replace everything from offset to the end of the
string, substr() should be called as follows:
substr(str, offset, strlen(str) - offset, replacement)
8.4. General Functions
The following POSIX standard library functions are provided:
strncmp()
strncasecmp()
strlen()
random()
sprintf()
sscanf()
9. International String Library
This library is optional for systems that wish to have support for
collating (sorting) and verifying equality of international strings
in a manner that will be least surprising to humans. International
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strings are encoded in the UTF-8 transformation format described in
[14]. This library is registered with the name
"pmInternationalStringLibrary".
When verifying equality of international strings in the Unicode
character set, it is recommended to normalize the strings with the
stringprep() function before checking for equality.
When attempting to sort international strings in the Unicode
character set, normalization should also be performed, but note that
the result is highly context dependent and hard to implement
correctly. Just ordering by Unicode Codepoint Value is in many cases
not what the end user expects. See Unicode technical note 9 for more
information about sorting.
9.1. stringprep()
integer stringprep(string utf8Input, string &utf8Output)
Performs the Stringprep [13] transformation for appropriate
comparison of internationalized strings. The transformation is
performed on 'utf8Input'; if the transformation finishes
without error, the resulting string is written to utf8Output.
The stringprep profile used is specified below in Section 9.
If it is successful, the function returns 1.
If the stringprep transformation encounters an error, 0 is
returned, and the utf8Output parameter remains unchanged.
For example, to compare UTF8 strings 'one' and 'two':
if (stringprep(one, a) && stringprep(two, b)){
if (a == b){
// strings are identical
} else {
// strings are different
}
} else {
// strings couldn't be transformed for comparison
}
See Stringprep [13] for more information.
9.1.1. Stringprep Profile
The Stringprep specification [13] describes a framework for preparing
Unicode text strings in order to increase the likelihood that string
input and string comparison work in ways that make sense for typical
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users throughout the world. Specifications that specify stringprep
(as this one does) are required to fully specify stringprep's
processing options by documenting a stringprep profile.
This profile defines the following, as required by Stringprep:
- The intended applicability of the profile: internationalized
network management information.
- The character repertoire that is the input and output to
stringprep: Unicode 3.2, as defined in Stringprep [13], Appendix
A.1.
- The mapping tables used: Table B.1 from Stringprep [13].
- Any additional mapping tables specific to the profile: None.
- The Unicode normalization used: Form KC, as described in Stringprep
[13].
- The characters that are prohibited as output: As specified in the
following tables from Stringprep [13]:
Table C.2
Table C.3
Table C.4
Table C.5
Table C.6
Table C.7
Table C.8
Table C.9
- Bidirectional character handling: not performed.
- Any additional characters that are prohibited as output: None.
9.2. utf8Strlen()
integer utf8Strlen(string str)
Returns the number of UTF-8 characters in 'str', which may be
less than the number of octets in 'str' if one or more
characters are multi-byte characters.
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9.3. utf8Chr()
string utf8Chr(integer utf8)
Returns a one-character string containing the character
specified by the UTF-8 code contained in 'utf8'. Although it
contains only 1 UTF-8 character, the resulting string may be
more than 1 octet in length.
9.4. utf8Ord()
integer utf8Ord(string str)
Returns the UTF-8 code-point value of the first character of
'str'. Note that the first UTF-8 character in 'str' may be
more than 1 octet in length. This function complements chr().
9.5. utf8Substr()
string utf8Substr(string &str, integer offset
[, integer len, string replacement])
Extracts a substring out of 'str' and returns it, keeping track
of UTF-8 character boundaries and using them, instead of
octets, as the basis for offset and length calculations. The
first character is at offset 0. If offset is negative, the
returned string starts that far from the end of 'str'. If
'len' is positive, the returned string contains up to 'len'
characters, up to the end of the string. If 'len' is omitted,
the returned string includes everything to the end of 'str'.
If 'len' is negative, abs(len) characters are left off the end
of the string.
If you specify a substring that is partly outside the string,
the part within the string is returned. If the substring is
totally outside the string, a zero-length string is produced.
If the optional 'replacement' argument is included, 'str' is
modified. 'offset' and 'len' act as above to select a range of
characters in 'str'. These characters are replaced with
characters from 'replacement'. If the replacement string is
shorter or longer than the number of characters selected, 'str'
will shrink or grow, respectively. If 'replacement' is
included, the 'len' argument must also be included.
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Note that to replace everything from offset to the end of the
string, substr() should be called as follows:
substr(str, offset, strlen(str) - offset, replacement)
10. Schedule Table
This table is an adapted form of the policyTimePeriodCondition class
defined in the Policy Core Information Model, RFC 3060 [18]. Some of
the objects describing a schedule are expressed in formats defined in
the iCalendar specification [15].
The policy schedule table allows control over when a valid policy
will be ready, based on the date and time.
A policy's pmPolicySchedule variable refers to a group of one or more
schedules in the schedule table. At any given time, if any of these
schedules are active, the policy will be ready (assuming that it is
enabled and thus valid), and its conditions and actions will be
executed, as appropriate. At times when none of these schedules are
active, the policy will not be ready and will have no effect. A
policy will always be ready if its pmPolicySchedule variable is 0.
If a policy has a non-zero pmPolicySchedule that doesn't refer to a
group that includes an active schedule, then the policy will not be
ready, even if this is due to a misconfiguration of the
pmPolicySchedule object or the pmSchedTable.
A policy that is controlled by a schedule group immediately executes
its policy condition (and conditionally the policyAction) when the
schedule group becomes active, periodically re-executing these
scripts as appropriate until the schedule group becomes inactive
(i.e., all schedules are inactive).
An individual schedule item is active at those times that match all
the variables that define the schedule: pmSchedTimePeriod,
pmSchedMonth, pmSchedDay, pmSchedWeekDay, and pmSchedTimeOfDay. It
is possible to specify multiple values for each schedule item. This
provides a mechanism for defining complex schedules. For example, a
schedule that is active the entire workday each weekday could be
defined.
Months, days, and weekdays are specified by using the objects
pmSchedMonth, pmSchedDay, and pmSchedWeekDay of type BITS. Setting
multiple bits in these objects causes an OR operation. For example,
setting the bits monday(1) and friday(5) in pmSchedWeekDay restricts
the schedule to Mondays and Fridays.
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The matched times for pmSchedTimePeriod, pmSchedMonth, pmSchedDay
pmSchedWeekDay, and pmSchedTimeOfDay are ANDed together to determine
the time periods when the schedule will be active; in other words,
the schedule is only active for those times when ALL of these
schedule attributes match. For example, a schedule with an overall
validity range of January 1, 2000, through December 31, 2000; a month
mask that selects March and April; a day-of-the-week mask that
selects Fridays; and a time-of-day range of 0800 through 1600 would
represent the following time periods:
Friday, March 5, 2000, from 0800 through 1600
Friday, March 12, 2000, from 0800 through 1600
Friday, March 19, 2000, from 0800 through 1600
Friday, March 26, 2000, from 0800 through 1600
Friday, April 2, 2000, from 0800 through 1600
Friday, April 9, 2000, from 0800 through 1600
Friday, April 16, 2000, from 0800 through 1600
Friday, April 23, 2000, from 0800 through 1600
Friday, April 30, 2000, from 0800 through 1600
Wildcarding of schedule attributes of type BITS is achieved by
setting all bits to one.
It is possible to define schedules that will never cause a policy to
be activated. For example, one can define a schedule that should be
active on February 31st.
11. Definitions
POLICY-BASED-MANAGEMENT-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, OBJECT-TYPE, NOTIFICATION-TYPE,
Counter32, Gauge32, Unsigned32,
mib-2 FROM SNMPv2-SMI
RowStatus, RowPointer, TEXTUAL-CONVENTION,
DateAndTime, StorageType FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP,
NOTIFICATION-GROUP FROM SNMPv2-CONF
SnmpAdminString FROM SNMP-FRAMEWORK-MIB;
-- Policy-Based Management MIB
pmMib MODULE-IDENTITY
LAST-UPDATED "200502070000Z" -- February 7, 2005
ORGANIZATION "IETF SNMP Configuration Working Group"
CONTACT-INFO
"
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Steve Waldbusser
Phone: +1-650-948-6500
Fax: +1-650-745-0671
Email: waldbusser@nextbeacon.com
Jon Saperia (WG Co-chair)
JDS Consulting, Inc.
84 Kettell Plain Road.
Stow MA 01775
USA
Phone: +1-978-461-0249
Fax: +1-617-249-0874
Email: saperia@jdscons.com
Thippanna Hongal
Riverstone Networks, Inc.
5200 Great America Parkway
Santa Clara, CA, 95054
USA
Phone: +1-408-878-6562
Fax: +1-408-878-6501
Email: hongal@riverstonenet.com
David Partain (WG Co-chair)
Postal: Ericsson AB
P.O. Box 1248
SE-581 12 Linkoping
Sweden
Tel: +46 13 28 41 44
E-mail: David.Partain@ericsson.com
Any questions or comments about this document can also be
directed to the working group at snmpconf@snmp.com."
DESCRIPTION
"The MIB module for policy-based configuration of SNMP
infrastructures.
Copyright (C) The Internet Society (2005). This version of
this MIB module is part of RFC 4011; see the RFC itself for
full legal notices."
REVISION "200502070000Z" -- February 7, 2005
DESCRIPTION
"The original version of this MIB, published as RFC4011."
::= { mib-2 124 }
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PmUTF8String ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"An octet string containing information typically in
human-readable form.
To facilitate internationalization, this
information is represented by using the ISO/IEC
IS 10646-1 character set, encoded as an octet
string using the UTF-8 transformation format
described in RFC 3629.
As additional code points are added by
amendments to the 10646 standard from time
to time, implementations must be prepared to
encounter any code point from 0x00000000 to
0x10FFFF. Byte sequences that do not
correspond to the valid UTF-8 encoding of a
code point or that are outside this range are
prohibited.
The use of control codes should be avoided.
When it is necessary to represent a newline,
the control code sequence CR LF should be used.
For code points not directly supported by user
interface hardware or software, an alternative
means of entry and display, such as hexadecimal,
may be provided.
For information encoded in 7-bit US-ASCII,
the UTF-8 encoding is identical to the
US-ASCII encoding.
UTF-8 may require multiple bytes to represent a
single character/code point; thus, the length
of this object in octets may be different from
the number of characters encoded. Similarly,
size constraints refer to the number of encoded
octets, not the number of characters represented
by an encoding.
Note that when this TC is used for an object
used or envisioned to be used as an index, then
a SIZE restriction MUST be specified so that the
number of sub-identifiers for any object instance
does not exceed the limit of 128, as defined by
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RFC 3416.
Note that the size of PmUTF8String object is
measured in octets, not characters."
SYNTAX OCTET STRING (SIZE (0..65535))
-- The policy table
pmPolicyTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmPolicyEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The policy table. A policy is a pairing of a
policyCondition and a policyAction that is used to apply the
action to a selected set of elements."
::= { pmMib 1 }
pmPolicyEntry OBJECT-TYPE
SYNTAX PmPolicyEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in the policy table representing one policy."
INDEX { pmPolicyAdminGroup, pmPolicyIndex }
::= { pmPolicyTable 1 }
PmPolicyEntry ::= SEQUENCE {
pmPolicyAdminGroup PmUTF8String,
pmPolicyIndex Unsigned32,
pmPolicyPrecedenceGroup PmUTF8String,
pmPolicyPrecedence Unsigned32,
pmPolicySchedule Unsigned32,
pmPolicyElementTypeFilter PmUTF8String,
pmPolicyConditionScriptIndex Unsigned32,
pmPolicyActionScriptIndex Unsigned32,
pmPolicyParameters OCTET STRING,
pmPolicyConditionMaxLatency Unsigned32,
pmPolicyActionMaxLatency Unsigned32,
pmPolicyMaxIterations Unsigned32,
pmPolicyDescription PmUTF8String,
pmPolicyMatches Gauge32,
pmPolicyAbnormalTerminations Gauge32,
pmPolicyExecutionErrors Counter32,
pmPolicyDebugging INTEGER,
pmPolicyAdminStatus INTEGER,
pmPolicyStorageType StorageType,
pmPolicyRowStatus RowStatus
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}
pmPolicyAdminGroup OBJECT-TYPE
SYNTAX PmUTF8String (SIZE(0..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An administratively assigned string that can be used to group
policies for convenience, for readability, or to simplify
configuration of access control.
The value of this string does not affect policy processing in
any way. If grouping is not desired or necessary, this object
may be set to a zero-length string."
::= { pmPolicyEntry 1 }
pmPolicyIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A unique index for this policy entry, unique among all
policies regardless of administrative group."
::= { pmPolicyEntry 2 }
pmPolicyPrecedenceGroup OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (0..32))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"An administratively assigned string that is used to group
policies. For each element, only one policy in the same
precedence group may be active on that element. If multiple
policies would be active on an element (because their
conditions return non-zero), the execution environment will
only allow the policy with the highest value of
pmPolicyPrecedence to be active.
All values of this object must have been successfully
transformed by Stringprep RFC 3454. Management stations
must perform this translation and must only set this object to
string values that have been transformed."
::= { pmPolicyEntry 3 }
pmPolicyPrecedence OBJECT-TYPE
SYNTAX Unsigned32 (0..65535)
MAX-ACCESS read-create
STATUS current
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DESCRIPTION
"If, while checking to see which policy conditions match an
element, 2 or more ready policies in the same precedence group
match the same element, the pmPolicyPrecedence object provides
the rule to arbitrate which single policy will be active on
'this element'. Of policies in the same precedence group, only
the ready and matching policy with the highest precedence
value (e.g., 2 is higher than 1) will have its policy action
periodically executed on 'this element'.
When a policy is active on an element but the condition ceases
to match the element, its action (if currently running) will
be allowed to finish and then the condition-matching ready
policy with the next-highest precedence will immediately
become active (and have its action run immediately). If the
condition of a higher-precedence ready policy suddenly begins
matching an element, the previously-active policy's action (if
currently running) will be allowed to finish and then the
higher precedence policy will immediately become active. Its
action will run immediately, and any lower-precedence matching
policy will not be active anymore.
In the case where multiple ready policies share the highest
value, it is an implementation-dependent matter as to which
single policy action will be chosen.
Note that if it is necessary to take certain actions after a
policy is no longer active on an element, these actions should
be included in a lower-precedence policy that is in the same
precedence group."
::= { pmPolicyEntry 4 }
pmPolicySchedule OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This policy will be ready if any of the associated schedule
entries are active.
If the value of this object is 0, this policy is always
ready.
If the value of this object is non-zero but doesn't
refer to a schedule group that includes an active schedule,
then the policy will not be ready, even if this is due to a
misconfiguration of this object or the pmSchedTable."
::= { pmPolicyEntry 5 }
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pmPolicyElementTypeFilter OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (0..128))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object specifies the element types for which this policy
can be executed.
The format of this object will be a sequence of
pmElementTypeRegOIDPrefix values, encoded in the following
BNF form:
elementTypeFilter: oid [ ';' oid ]*
oid: subid [ '.' subid ]*
subid: '0' | decimal_constant
For example, to register for the policy to be run on all
interface elements, the 'ifEntry' element type will be
registered as '1.3.6.1.2.1.2.2.1'.
If a value is included that does not represent a registered
pmElementTypeRegOIDPrefix, then that value will be ignored."
::= { pmPolicyEntry 6 }
pmPolicyConditionScriptIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A pointer to the row or rows in the pmPolicyCodeTable that
contain the condition code for this policy. When a policy
entry is created, a pmPolicyCodeIndex value unused by this
policy's adminGroup will be assigned to this object.
A policy condition is one or more PolicyScript statements
that result(s) in a boolean value that represents whether
an element is a member of a set of elements upon which an
action is to be performed. If a policy is ready and the
condition returns true for an element of a proper element
type, and if no higher-precedence policy should be active,
then the policy is active on that element.
Condition evaluation stops immediately when any run-time
exception is detected, and the policyAction is not executed.
The policyCondition is evaluated for various elements. Any
element for which the policyCondition returns any nonzero value
will match the condition and will have the associated
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policyAction executed on that element unless a
higher-precedence policy in the same precedence group also
matches 'this element'.
If the condition object is empty (contains no code) or
otherwise does not return a value, the element will not be
matched.
When this condition is executed, if SNMP requests are made to
the local system and secModel/secName/secLevel aren't
specified, access to objects is under the security
credentials of the requester who most recently modified the
associated pmPolicyAdminStatus object. If SNMP requests are
made in which secModel/secName/secLevel are specified, then
the specified credentials are retrieved from the local
configuration datastore only if VACM is configured to
allow access to the requester who most recently modified the
associated pmPolicyAdminStatus object. See the Security
Considerations section for more information."
::= { pmPolicyEntry 7 }
pmPolicyActionScriptIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A pointer to the row or rows in the pmPolicyCodeTable that
contain the action code for this policy. When a policy entry
is created, a pmPolicyCodeIndex value unused by this policy's
adminGroup will be assigned to this object.
A PolicyAction is an operation performed on a
set of elements for which the policy is active.
Action evaluation stops immediately when any run-time
exception is detected.
When this condition is executed, if SNMP requests are made to
the local system and secModel/secName/secLevel aren't
specified, access to objects is under the security
credentials of the requester who most recently modified the
associated pmPolicyAdminStatus object. If SNMP requests are
made in which secModel/secName/secLevel are specified, then
the specified credentials are retrieved from the local
configuration datastore only if VACM is configured to
allow access to the requester who most recently modified the
associated pmPolicyAdminStatus object. See the Security
Considerations section for more information."
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::= { pmPolicyEntry 8 }
pmPolicyParameters OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (0..65535))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"From time to time, policy scripts may seek one or more
parameters (e.g., site-specific constants). These parameters
may be installed with the script in this object and are
accessible to the script via the getParameters() function. If
it is necessary for multiple parameters to be passed to the
script, the script can choose whatever encoding/delimiting
mechanism is most appropriate."
::= { pmPolicyEntry 9 }
pmPolicyConditionMaxLatency OBJECT-TYPE
SYNTAX Unsigned32 (0..2147483647)
UNITS "milliseconds"
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Every element under the control of this agent is
re-checked periodically to see whether it is under control
of this policy by re-running the condition for this policy.
This object lets the manager control the maximum amount of
time that may pass before an element is re-checked.
In other words, in any given interval of this duration, all
elements must be re-checked. Note that how the policy agent
schedules the checking of various elements within this
interval is an implementation-dependent matter.
Implementations may wish to re-run a condition more
quickly if they note a change to the role strings for an
element."
::= { pmPolicyEntry 10 }
pmPolicyActionMaxLatency OBJECT-TYPE
SYNTAX Unsigned32 (0..2147483647)
UNITS "milliseconds"
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Every element that matches this policy's condition and is
therefore under control of this policy will have this policy's
action executed periodically to ensure that the element
remains in the state dictated by the policy.
This object lets the manager control the maximum amount of
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time that may pass before an element has the action run on
it.
In other words, in any given interval of this duration, all
elements under control of this policy must have the action run
on them. Note that how the policy agent schedules the policy
action on various elements within this interval is an
implementation-dependent matter."
::= { pmPolicyEntry 11 }
pmPolicyMaxIterations OBJECT-TYPE
SYNTAX Unsigned32
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"If a condition or action script iterates in loops too many
times in one invocation, the execution environment may
consider it in an infinite loop or otherwise not acting
as intended and may be terminated by the execution
environment. The execution environment will count the
cumulative number of times all 'for' or 'while' loops iterated
and will apply a threshold to determine when to terminate the
script. What threshold the execution environment uses is an
implementation-dependent manner, but the value of
this object SHOULD be the basis for choosing the threshold for
each script. The value of this object represents a
policy-specific threshold and can be tuned for policies of
varying workloads. If this value is zero, no
threshold will be enforced except for any
implementation-dependent maximum. Regardless of this value,
the agent is allowed to terminate any script invocation that
exceeds a local CPU or memory limitation.
Note that the condition and action invocations are tracked
separately."
::= { pmPolicyEntry 12 }
pmPolicyDescription OBJECT-TYPE
SYNTAX PmUTF8String
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A description of this rule and its significance, typically
provided by a human."
::= { pmPolicyEntry 13 }
pmPolicyMatches OBJECT-TYPE
SYNTAX Gauge32
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UNITS "elements"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of elements that, in their most recent execution
of the associated condition, were matched by the condition."
::= { pmPolicyEntry 14 }
pmPolicyAbnormalTerminations OBJECT-TYPE
SYNTAX Gauge32
UNITS "elements"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of elements that, in their most recent execution
of the associated condition or action, have experienced a
run-time exception and terminated abnormally. Note that if a
policy was experiencing a run-time exception while processing
a particular element but runs normally on a subsequent
invocation, this number can decline."
::= { pmPolicyEntry 15 }
pmPolicyExecutionErrors OBJECT-TYPE
SYNTAX Counter32
UNITS "errors"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of times that execution of this policy's
condition or action has been terminated due to run-time
exceptions."
::= { pmPolicyEntry 16 }
pmPolicyDebugging OBJECT-TYPE
SYNTAX INTEGER {
off(1),
on(2)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of debugging for this policy. If this is turned
on(2), log entries will be created in the pmDebuggingTable
for each run-time exception that is experienced by this
policy."
DEFVAL { off }
::= { pmPolicyEntry 17 }
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pmPolicyAdminStatus OBJECT-TYPE
SYNTAX INTEGER {
disabled(1),
enabled(2),
enabledAutoRemove(3)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The administrative status of this policy.
The policy will be valid only if the associated
pmPolicyRowStatus is set to active(1) and this object is set
to enabled(2) or enabledAutoRemove(3).
If this object is set to enabledAutoRemove(3), the next time
the associated schedule moves from the active state to the
inactive state, this policy will immediately be deleted,
including any associated entries in the pmPolicyCodeTable.
The following related objects may not be changed unless this
object is set to disabled(1):
pmPolicyPrecedenceGroup, pmPolicyPrecedence,
pmPolicySchedule, pmPolicyElementTypeFilter,
pmPolicyConditionScriptIndex, pmPolicyActionScriptIndex,
pmPolicyParameters, and any pmPolicyCodeTable row
referenced by this policy.
In order to change any of these parameters, the policy must
be moved to the disabled(1) state, changed, and then
re-enabled.
When this policy moves to either enabled state from the
disabled state, any cached values of policy condition must be
erased, and any Policy or PolicyElement scratchpad values for
this policy should be removed. Policy execution will begin by
testing the policy condition on all appropriate elements."
::= { pmPolicyEntry 18 }
pmPolicyStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object defines whether this policy and any associated
entries in the pmPolicyCodeTable are kept in volatile storage
and lost upon reboot or if this row is backed up by
non-volatile or permanent storage.
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If the value of this object is 'permanent', the values for
the associated pmPolicyAdminStatus object must remain
writable."
::= { pmPolicyEntry 19 }
pmPolicyRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The row status of this pmPolicyEntry.
The status may not be set to active if any of the related
entries in the pmPolicyCode table do not have a status of
active or if any of the objects in this row are not set to
valid values. Only the following objects may be modified
while in the active state:
pmPolicyParameters
pmPolicyConditionMaxLatency
pmPolicyActionMaxLatency
pmPolicyDebugging
pmPolicyAdminStatus
If this row is deleted, any associated entries in the
pmPolicyCodeTable will be deleted as well."
::= { pmPolicyEntry 20 }
-- Policy Code Table
pmPolicyCodeTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmPolicyCodeEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The pmPolicyCodeTable stores the code for policy conditions and
actions.
An example of the relationships between the code table and the
policy table follows:
pmPolicyTable
AdminGroup Index ConditionScriptIndex ActionScriptIndex
A '' 1 1 2
B 'oper' 1 1 2
C 'oper' 2 3 4
pmPolicyCodeTable
AdminGroup ScriptIndex Segment Note
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'' 1 1 Filter for policy A
'' 2 1 Action for policy A
'oper' 1 1 Filter for policy B
'oper' 2 1 Action 1/2 for policy B
'oper' 2 2 Action 2/2 for policy B
'oper' 3 1 Filter for policy C
'oper' 4 1 Action for policy C
In this example, there are 3 policies: 1 in the '' adminGroup,
and 2 in the 'oper' adminGroup. Policy A has been assigned
script indexes 1 and 2 (these script indexes are assigned out of
a separate pool per adminGroup), with 1 code segment each for
the filter and the action. Policy B has been assigned script
indexes 1 and 2 (out of the pool for the 'oper' adminGroup).
While the filter has 1 segment, the action is longer and is
loaded into 2 segments. Finally, Policy C has been assigned
script indexes 3 and 4, with 1 code segment each for the filter
and the action."
::= { pmMib 2 }
pmPolicyCodeEntry OBJECT-TYPE
SYNTAX PmPolicyCodeEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in the policy code table representing one code
segment. Entries that share a common AdminGroup/ScriptIndex
pair make up a single script. Valid values of ScriptIndex are
retrieved from pmPolicyConditionScriptIndex and
pmPolicyActionScriptIndex after a pmPolicyEntry is
created. Segments of code can then be written to this table
with the learned ScriptIndex values.
The StorageType of this entry is determined by the value of
the associated pmPolicyStorageType.
The pmPolicyAdminGroup element of the index represents the
administrative group of the policy of which this code entry is
a part."
INDEX { pmPolicyAdminGroup, pmPolicyCodeScriptIndex,
pmPolicyCodeSegment }
::= { pmPolicyCodeTable 1 }
PmPolicyCodeEntry ::= SEQUENCE {
pmPolicyCodeScriptIndex Unsigned32,
pmPolicyCodeSegment Unsigned32,
pmPolicyCodeText PmUTF8String,
pmPolicyCodeStatus RowStatus
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}
pmPolicyCodeScriptIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A unique index for each policy condition or action. The code
for each such condition or action may be composed of multiple
entries in this table if the code cannot fit in one entry.
Values of pmPolicyCodeScriptIndex may not be used unless
they have previously been assigned in the
pmPolicyConditionScriptIndex or pmPolicyActionScriptIndex
objects."
::= { pmPolicyCodeEntry 1 }
pmPolicyCodeSegment OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A unique index for each segment of a policy condition or
action.
When a policy condition or action spans multiple entries in
this table, the code of that policy starts from the
lowest-numbered segment and continues with increasing segment
values until it ends with the highest-numbered segment."
::= { pmPolicyCodeEntry 2 }
pmPolicyCodeText OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (1..1024))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A segment of policy code (condition or action). Lengthy
Policy conditions or actions may be stored in multiple
segments in this table that share the same value of
pmPolicyCodeScriptIndex. When multiple segments are used, it
is recommended that each segment be as large as is practical.
Entries in this table are associated with policies by values
of the pmPolicyConditionScriptIndex and
pmPolicyActionScriptIndex objects. If the status of the
related policy is active, then this object may not be
modified."
::= { pmPolicyCodeEntry 3 }
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pmPolicyCodeStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this code entry.
Entries in this table are associated with policies by values
of the pmPolicyConditionScriptIndex and
pmPolicyActionScriptIndex objects. If the status of the
related policy is active, then this object can not be
modified (i.e., deleted or set to notInService), nor may new
entries be created.
If the status of this object is active, no objects in this
row may be modified."
::= { pmPolicyCodeEntry 4 }
-- Element Type Registration Table
pmElementTypeRegTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmElementTypeRegEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A registration table for element types managed by this
system.
The Element Type Registration table allows the manager to
learn what element types are being managed by the system and
to register new types, if necessary. An element type is
registered by providing the OID of an SNMP object (i.e.,
without the instance). Each SNMP instance that exists under
that object is a distinct element. The index of the element is
the index part of the discovered OID. This index will be
supplied to policy conditions and actions so that this code
can inspect and configure the element.
For example, this table might contain the following entries.
The first three are agent-installed, and the 4th was
downloaded by a management station:
OIDPrefix MaxLatency Description StorageType
ifEntry 100 mS interfaces - builtin readOnly
0.0 100 mS system element - builtin readOnly
frCircuitEntry 100 mS FR Circuits - builtin readOnly
hrSWRunEntry 60 sec Running Processes volatile
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Note that agents may automatically configure elements in this
table for frequently used element types (interfaces, circuits,
etc.). In particular, it may configure elements for whom
discovery is optimized in one or both of the following ways:
1. The agent may discover elements by scanning internal data
structures as opposed to issuing local SNMP requests. It is
possible to recreate the exact semantics described in this
table even if local SNMP requests are not issued.
2. The agent may receive asynchronous notification of new
elements (for example, 'card inserted') and use that
information to instantly create elements rather than
through polling. A similar feature might be available for
the deletion of elements.
Note that the disposition of agent-installed entries is
described by the pmPolicyStorageType object."
::= { pmMib 3 }
pmElementTypeRegEntry OBJECT-TYPE
SYNTAX PmElementTypeRegEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A registration of an element type.
Note that some values of this table's index may result in an
instance name that exceeds a length of 128 sub-identifiers,
which exceeds the maximum for the SNMP protocol.
Implementations should take care to avoid such values."
INDEX { pmElementTypeRegOIDPrefix }
::= { pmElementTypeRegTable 1 }
PmElementTypeRegEntry ::= SEQUENCE {
pmElementTypeRegOIDPrefix OBJECT IDENTIFIER,
pmElementTypeRegMaxLatency Unsigned32,
pmElementTypeRegDescription PmUTF8String,
pmElementTypeRegStorageType StorageType,
pmElementTypeRegRowStatus RowStatus
}
pmElementTypeRegOIDPrefix OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This OBJECT IDENTIFIER value identifies a table in which all
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elements of this type will be found. Every row in the
referenced table will be treated as an element for the
period of time that it remains in the table. The agent will
then execute policy conditions and actions as appropriate on
each of these elements.
This object identifier value is specified down to the 'entry'
component (e.g., ifEntry) of the identifier.
The index of each discovered row will be passed to each
invocation of the policy condition and policy action.
The actual mechanism by which instances are discovered is
implementation dependent. Periodic walks of the table to
discover the rows in the table is one such mechanism. This
mechanism has the advantage that it can be performed by an
agent with no knowledge of the names, syntax, or semantics
of the MIB objects in the table. This mechanism also serves as
the reference design. Other implementation-dependent
mechanisms may be implemented that are more efficient (perhaps
because they are hard coded) or that don't require polling.
These mechanisms must discover the same elements as would the
table-walking reference design.
This object can contain a OBJECT IDENTIFIER, '0.0'.
'0.0' represents the single instance of the system
itself and provides an execution context for policies to
operate on the 'system element' and on MIB objects
modeled as scalars. For example, '0.0' gives an execution
context for policy-based selection of the operating system
code version (likely modeled as a scalar MIB object). The
element type '0.0' always exists; as a consequence, no actual
discovery will take place, and the pmElementTypeRegMaxLatency
object will have no effect for the '0.0' element
type. However, if the '0.0' element type is not registered in
the table, policies will not be executed on the '0.0' element.
When a policy is invoked on behalf of a '0.0' entry in this
table, the element name will be '0.0', and there is no index
of 'this element' (in other words, it has zero length).
As this object is used in the index for the
pmElementTypeRegTable, users of this table should be careful
not to create entries that would result in instance names with
more than 128 sub-identifiers."
::= { pmElementTypeRegEntry 2 }
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pmElementTypeRegMaxLatency OBJECT-TYPE
SYNTAX Unsigned32
UNITS "milliseconds"
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The PM agent is responsible for discovering new elements of
types that are registered. This object lets the manager
control the maximum amount of time that may pass between the
time an element is created and when it is discovered.
In other words, in any given interval of this duration, all
new elements must be discovered. Note that how the policy
agent schedules the checking of various elements within this
interval is an implementation-dependent matter."
::= { pmElementTypeRegEntry 3 }
pmElementTypeRegDescription OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (0..64))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A descriptive label for this registered type."
::= { pmElementTypeRegEntry 4 }
pmElementTypeRegStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object defines whether this row is kept
in volatile storage and lost upon reboot or
backed up by non-volatile or permanent storage.
If the value of this object is 'permanent', no values in the
associated row have to be writable."
::= { pmElementTypeRegEntry 5 }
pmElementTypeRegRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this registration entry.
If the value of this object is active, no objects in this row
may be modified."
::= { pmElementTypeRegEntry 6 }
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-- Role Table
pmRoleTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmRoleEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The pmRoleTable is a read-create table that organizes role
strings sorted by element. This table is used to create and
modify role strings and their associations, as well as to allow
a management station to learn about the existence of roles and
their associations.
It is the responsibility of the agent to keep track of any
re-indexing of the underlying SNMP elements and to continue to
associate role strings with the element with which they were
initially configured.
Policy MIB agents that have elements in multiple local SNMP
contexts have to allow some roles to be assigned to elements
in particular contexts. This is particularly true when some
elements have the same names in different contexts and the
context is required to disambiguate them. In those situations,
a value for the pmRoleContextName may be provided. When a
pmRoleContextName value is not provided, the assignment is to
the element in the default context.
Policy MIB agents that discover elements on other systems and
execute policies on their behalf need to have access to role
information for these remote elements. In such situations,
role assignments for other systems can be stored in this table
by providing values for the pmRoleContextEngineID parameters.
For example:
Example:
element role context ctxEngineID #comment
ifindex.1 gold local, default context
ifindex.2 gold local, default context
repeaterid.1 foo rptr1 local, rptr1 context
repeaterid.1 bar rptr2 local, rptr2 context
ifindex.1 gold '' A different system
ifindex.1 gold '' B different system
The agent must store role string associations in non-volatile
storage."
::= { pmMib 4 }
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pmRoleEntry OBJECT-TYPE
SYNTAX PmRoleEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A role string entry associates a role string with an
individual element.
Note that some combinations of index values may result in an
instance name that exceeds a length of 128 sub-identifiers,
which exceeds the maximum for the SNMP
protocol. Implementations should take care to avoid such
combinations."
INDEX { pmRoleElement, pmRoleContextName,
pmRoleContextEngineID, pmRoleString }
::= { pmRoleTable 1 }
PmRoleEntry ::= SEQUENCE {
pmRoleElement RowPointer,
pmRoleContextName SnmpAdminString,
pmRoleContextEngineID OCTET STRING,
pmRoleString PmUTF8String,
pmRoleStatus RowStatus
}
pmRoleElement OBJECT-TYPE
SYNTAX RowPointer
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The element with which this role string is associated.
For example, if the element is interface 3, then this object
will contain the OID for 'ifIndex.3'.
If the agent assigns new indexes in the MIB table to
represent the same underlying element (re-indexing), the
agent will modify this value to contain the new index for the
underlying element.
As this object is used in the index for the pmRoleTable,
users of this table should be careful not to create entries
that would result in instance names with more than 128
sub-identifiers."
::= { pmRoleEntry 1 }
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pmRoleContextName OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE (0..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is not in the default SNMP context
for the target system, this object is used to identify the
context. If the element is in the default context, this object
is equal to the empty string."
::= { pmRoleEntry 2 }
pmRoleContextEngineID OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (0 | 5..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is on a remote system, this object
is used to identify the remote system. This object contains
the contextEngineID of the system for which this role string
assignment is valid. If the element is on the local system
this object will be the empty string."
::= { pmRoleEntry 3 }
pmRoleString OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (0..64))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The role string that is associated with an element through
this table. All role strings must have been successfully
transformed by Stringprep RFC 3454. Management stations
must perform this translation and must only set this object
to string values that have been transformed.
A role string is an administratively specified characteristic
of a managed element (for example, an interface). It is a
selector for policy rules, that determines the applicability of
the rule to a particular managed element."
::= { pmRoleEntry 4 }
pmRoleStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this role string.
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If the value of this object is active, no object in this row
may be modified."
::= { pmRoleEntry 5 }
-- Capabilities table
pmCapabilitiesTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmCapabilitiesEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The pmCapabilitiesTable contains a description of
the inherent capabilities of the system so that
management stations can learn of an agent's capabilities and
differentially install policies based on the capabilities.
Capabilities are expressed at the system level. There can be
variation in how capabilities are realized from one vendor or
model to the next. Management systems should consider these
differences before selecting which policy to install in a
system."
::= { pmMib 5 }
pmCapabilitiesEntry OBJECT-TYPE
SYNTAX PmCapabilitiesEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A capabilities entry holds an OID indicating support for a
particular capability. Capabilities may include hardware and
software functions and the implementation of MIB
Modules. The semantics of the OID are defined in the
description of pmCapabilitiesType.
Entries appear in this table if any element in the system has
a specific capability. A capability should appear in this
table only once, regardless of the number of elements in the
system with that capability. An entry is removed from this
table when the last element in the system that has the
capability is removed. In some cases, capabilities are
dynamic and exist only in software. This table should have an
entry for the capability even if there are no current
instances. Examples include systems with database or WEB
services. While the system has the ability to create new
databases or WEB services, the entry should exist. In these
cases, the ability to create these services could come from
other processes that are running in the system, even though
there are no currently open databases or WEB servers running.
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Capabilities may include the implementation of MIB Modules
but need not be limited to those that represent MIB Modules
with one or more configurable objects. It may also be
valuable to include entries for capabilities that do not
include configuration objects, as that information, in
combination with other entries in this table, might be used
by the management software to determine whether to
install a policy.
Vendor software may also add entries in this table to express
capabilities from their private branch.
Note that some values of this table's index may result in an
instance name that exceeds a length of 128 sub-identifiers,
which exceeds the maximum for the SNMP
protocol. Implementations should take care to avoid such
values."
INDEX { pmCapabilitiesType }
::= { pmCapabilitiesTable 1 }
PmCapabilitiesEntry ::= SEQUENCE {
pmCapabilitiesType OBJECT IDENTIFIER
}
pmCapabilitiesType OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"There are three types of OIDs that may be present in the
pmCapabilitiesType object:
1) The OID of a MODULE-COMPLIANCE macro that represents the
highest level of compliance realized by the agent for that
MIB Module. For example, an agent that implements the OSPF
MIB Module at the highest level of compliance would have the
value of '1.3.6.1.2.1.14.15.2' in the pmCapabilitiesType
object. For software that realizes standard MIB
Modules that do not have compliance statements, the base OID
of the MIB Module should be used instead. If the OSPF MIB
Module had not been created with a compliance statement, then
the correct value of the pmCapabilitiesType would be
'1.3.6.1.2.1.14'. In the cases where multiple compliance
statements in a MIB Module are supported by the agent, and
where one compliance statement does not by definition include
the other, each of the compliance OIDs would have entries in
this table.
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MIB Documents can contain more than one MIB Module. In the
case of OSPF, there is a second MIB Module
that describes notifications for the OSPF Version 2 Protocol.
If the agent also realizes these functions, an entry will
also exist for those capabilities in this table.
2) Vendors should install OIDs in this table that represent
vendor-specific capabilities. These capabilities can be
expressed just as those described above for MIB Modules on
the standards track. In addition, vendors may install any
OID they desire from their registered branch. The OIDs may be
at any level of granularity, from the root of their entire
branch to an instance of a single OID. There is no
restriction on the number of registrations they may make,
though care should be taken to avoid unnecessary entries.
3) OIDs that represent one capability or a collection of
capabilities that could be any collection of MIB Objects or
hardware or software functions may be created in working
groups and registered in a MIB Module. Other entities (e.g.,
vendors) may also make registrations. Software will register
these standard capability OIDs, as well as vendor specific
OIDs.
If the OID for a known capability is not present in the
table, then it should be assumed that the capability is not
implemented.
As this object is used in the index for the
pmCapabilitiesTable, users of this table should be careful
not to create entries that would result in instance names
with more than 128 sub-identifiers."
::= { pmCapabilitiesEntry 1 }
-- Capabilities override table
pmCapabilitiesOverrideTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmCapabilitiesOverrideEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The pmCapabilitiesOverrideTable allows management stations
to override pmCapabilitiesTable entries that have been
registered by the agent. This facility can be used to avoid
situations in which managers in the network send policies to
a system that has advertised a capability in the
pmCapabilitiesTable but that should not be installed on this
particular system. One example could be newly deployed
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equipment that is still in a trial state in a trial state or
resources reserved for some other administrative reason.
This table can also be used to override entries in the
pmCapabilitiesTable through the use of the
pmCapabilitiesOverrideState object. Capabilities can also be
declared available in this table that were not registered in
the pmCapabilitiesTable. A management application can make
an entry in this table for any valid OID and declare the
capability available by setting the
pmCapabilitiesOverrideState for that row to valid(1)."
::= { pmMib 6 }
pmCapabilitiesOverrideEntry OBJECT-TYPE
SYNTAX PmCapabilitiesOverrideEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in this table indicates whether a particular
capability is valid or invalid.
Note that some values of this table's index may result in an
instance name that exceeds a length of 128 sub-identifiers,
which exceeds the maximum for the SNMP
protocol. Implementations should take care to avoid such
values."
INDEX { pmCapabilitiesOverrideType }
::= { pmCapabilitiesOverrideTable 1 }
PmCapabilitiesOverrideEntry ::= SEQUENCE {
pmCapabilitiesOverrideType OBJECT IDENTIFIER,
pmCapabilitiesOverrideState INTEGER,
pmCapabilitiesOverrideRowStatus RowStatus
}
pmCapabilitiesOverrideType OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This is the OID of the capability that is declared valid or
invalid by the pmCapabilitiesOverrideState value for this
row. Any valid OID, as described in the pmCapabilitiesTable,
is permitted in the pmCapabilitiesOverrideType object. This
means that capabilities can be expressed at any level, from a
specific instance of an object to a table or entire module.
There are no restrictions on whether these objects are from
standards track MIB documents or in the private branch of the
MIB.
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If an entry exists in this table for which there is a
corresponding entry in the pmCapabilitiesTable, then this entry
shall have precedence over the entry in the
pmCapabilitiesTable. All entries in this table must be
preserved across reboots.
As this object is used in the index for the
pmCapabilitiesOverrideTable, users of this table should be
careful not to create entries that would result in instance
names with more than 128 sub-identifiers."
::= { pmCapabilitiesOverrideEntry 1 }
pmCapabilitiesOverrideState OBJECT-TYPE
SYNTAX INTEGER {
invalid(1),
valid(2)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"A pmCapabilitiesOverrideState of invalid indicates that
management software should not send policies to this system
for the capability identified in the
pmCapabilitiesOverrideType for this row of the table. This
behavior is the same whether the capability represented by
the pmCapabilitiesOverrideType exists only in this table
(that is, it was installed by an external management
application) or exists in this table as well as the
pmCapabilitiesTable. This would be the case when a manager
wanted to disable a capability that the native management
system found and registered in the pmCapabilitiesTable.
An entry in this table that has a pmCapabilitiesOverrideState
of valid should be treated as though it appeared in the
pmCapabilitiesTable. If the entry also exists in the
pmCapabilitiesTable in the pmCapabilitiesType object, and if
the value of this object is valid, then the system shall
operate as though this entry did not exist and policy
installations and executions will continue in a normal
fashion."
::= { pmCapabilitiesOverrideEntry 2 }
pmCapabilitiesOverrideRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The row status of this pmCapabilitiesOverrideEntry.
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If the value of this object is active, no object in this row
may be modified."
::= { pmCapabilitiesOverrideEntry 3 }
-- The Schedule Group
pmSchedLocalTime OBJECT-TYPE
SYNTAX DateAndTime (SIZE (11))
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The local time used by the scheduler. Schedules that
refer to calendar time will use the local time indicated
by this object. An implementation MUST return all 11 bytes
of the DateAndTime textual-convention so that a manager
may retrieve the offset from GMT time."
::= { pmMib 7 }
--
-- The schedule table that controls the scheduler.
--
pmSchedTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmSchedEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table defines schedules for policies."
::= { pmMib 8 }
pmSchedEntry OBJECT-TYPE
SYNTAX PmSchedEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry describing a particular schedule.
Unless noted otherwise, writable objects of this row can be
modified independently of the current value of pmSchedRowStatus,
pmSchedAdminStatus and pmSchedOperStatus. In particular, it
is legal to modify pmSchedWeekDay, pmSchedMonth, and
pmSchedDay when pmSchedRowStatus is active."
INDEX { pmSchedIndex }
::= { pmSchedTable 1 }
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PmSchedEntry ::= SEQUENCE {
pmSchedIndex Unsigned32,
pmSchedGroupIndex Unsigned32,
pmSchedDescr PmUTF8String,
pmSchedTimePeriod PmUTF8String,
pmSchedMonth BITS,
pmSchedDay BITS,
pmSchedWeekDay BITS,
pmSchedTimeOfDay PmUTF8String,
pmSchedLocalOrUtc INTEGER,
pmSchedStorageType StorageType,
pmSchedRowStatus RowStatus
}
pmSchedIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The locally unique, administratively assigned index for this
scheduling entry."
::= { pmSchedEntry 1 }
pmSchedGroupIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The locally unique, administratively assigned index for the
schedule group this scheduling entry belongs to.
To assign multiple schedule entries to the same group, the
pmSchedGroupIndex of each entry in the group will be set to
the same value. This pmSchedGroupIndex value must be equal to
the pmSchedIndex of one of the entries in the group. If the
entry whose pmSchedIndex equals the pmSchedGroupIndex
for the group is deleted, the agent will assign a new
pmSchedGroupIndex to all remaining members of the group.
If an entry is not a member of a group, its pmSchedGroupIndex
must be assigned to the value of its pmSchedIndex.
Policies that are controlled by a group of schedule entries
are active when any schedule in the group is active."
::= { pmSchedEntry 2 }
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pmSchedDescr OBJECT-TYPE
SYNTAX PmUTF8String
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The human-readable description of the purpose of this
scheduling entry."
DEFVAL { ''H }
::= { pmSchedEntry 3 }
pmSchedTimePeriod OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (0..31))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The overall range of calendar dates and times over which this
schedule is active. It is stored in a slightly extended version
of the format for a 'period-explicit' defined in RFC 2445.
This format is expressed as a string representing the
starting date and time, in which the character 'T' indicates
the beginning of the time portion, followed by the solidus
character, '/', followed by a similar string representing an
end date and time. The start of the period MUST be before the
end of the period. Date-Time values are expressed as
substrings of the form 'yyyymmddThhmmss'. For example:
20000101T080000/20000131T130000
January 1, 2000, 0800 through January 31, 2000, 1PM
The 'Date with UTC time' format defined in RFC 2445 in which
the Date-Time string ends with the character 'Z' is not
allowed.
This 'period-explicit' format is also extended to allow two
special cases in which one of the Date-Time strings is
replaced with a special string defined in RFC 2445:
1. If the first Date-Time value is replaced with the string
'THISANDPRIOR', then the value indicates that the schedule
is active at any time prior to the Date-Time that appears
after the '/'.
2. If the second Date-Time is replaced with the string
'THISANDFUTURE', then the value indicates that the schedule
is active at any time after the Date-Time that appears
before the '/'.
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Note that although RFC 2445 defines these two strings, they are
not specified for use in the 'period-explicit' format. The use
of these strings represents an extension to the
'period-explicit' format."
::= { pmSchedEntry 4 }
pmSchedMonth OBJECT-TYPE
SYNTAX BITS {
january(0),
february(1),
march(2),
april(3),
may(4),
june(5),
july(6),
august(7),
september(8),
october(9),
november(10),
december(11)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Within the overall time period specified in the
pmSchedTimePeriod object, the value of this object specifies
the specific months within that time period when the schedule
is active. Setting all bits will cause the schedule to act
independently of the month."
DEFVAL { { january, february, march, april, may, june, july,
august, september, october, november, december } }
::= { pmSchedEntry 5 }
pmSchedDay OBJECT-TYPE
SYNTAX BITS {
d1(0), d2(1), d3(2), d4(3), d5(4),
d6(5), d7(6), d8(7), d9(8), d10(9),
d11(10), d12(11), d13(12), d14(13), d15(14),
d16(15), d17(16), d18(17), d19(18), d20(19),
d21(20), d22(21), d23(22), d24(23), d25(24),
d26(25), d27(26), d28(27), d29(28), d30(29),
d31(30),
r1(31), r2(32), r3(33), r4(34), r5(35),
r6(36), r7(37), r8(38), r9(39), r10(40),
r11(41), r12(42), r13(43), r14(44), r15(45),
r16(46), r17(47), r18(48), r19(49), r20(50),
r21(51), r22(52), r23(53), r24(54), r25(55),
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r26(56), r27(57), r28(58), r29(59), r30(60),
r31(61)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Within the overall time period specified in the
pmSchedTimePeriod object, the value of this object specifies
the specific days of the month within that time period when
the schedule is active.
There are two sets of bits one can use to define the day
within a month:
Enumerations starting with the letter 'd' indicate a
day in a month relative to the first day of a month.
The first day of the month can therefore be specified
by setting the bit d1(0), and d31(30) means the last
day of a month with 31 days.
Enumerations starting with the letter 'r' indicate a
day in a month in reverse order, relative to the last
day of a month. The last day in the month can therefore
be specified by setting the bit r1(31), and r31(61) means
the first day of a month with 31 days.
Setting multiple bits will include several days in the set
of possible days for this schedule. Setting all bits starting
with the letter 'd' or all bits starting with the letter 'r'
will cause the schedule to act independently of the day of the
month."
DEFVAL { { d1, d2, d3, d4, d5, d6, d7, d8, d9, d10,
d11, d12, d13, d14, d15, d16, d17, d18, d19, d20,
d21, d22, d23, d24, d25, d26, d27, d28, d29, d30,
d31, r1, r2, r3, r4, r5, r6, r7, r8, r9, r10,
r11, r12, r13, r14, r15, r16, r17, r18, r19, r20,
r21, r22, r23, r24, r25, r26, r27, r28, r29, r30,
r31 } }
::= { pmSchedEntry 6 }
pmSchedWeekDay OBJECT-TYPE
SYNTAX BITS {
sunday(0),
monday(1),
tuesday(2),
wednesday(3),
thursday(4),
friday(5),
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saturday(6)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Within the overall time period specified in the
pmSchedTimePeriod object, the value of this object specifies
the specific days of the week within that time period when
the schedule is active. Setting all bits will cause the
schedule to act independently of the day of the week."
DEFVAL { { sunday, monday, tuesday, wednesday, thursday,
friday, saturday } }
::= { pmSchedEntry 7 }
pmSchedTimeOfDay OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (0..15))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"Within the overall time period specified in the
pmSchedTimePeriod object, the value of this object specifies
the range of times in a day when the schedule is active.
This value is stored in a format based on the RFC 2445 format
for 'time': The character 'T' followed by a 'time' string,
followed by the solidus character, '/', followed by the
character 'T', followed by a second time string. The first time
indicates the beginning of the range, and the second time
indicates the end. Thus, this value takes the following
form:
'Thhmmss/Thhmmss'.
The second substring always identifies a later time than the
first substring. To allow for ranges that span midnight,
however, the value of the second string may be smaller than
the value of the first substring. Thus, 'T080000/T210000'
identifies the range from 0800 until 2100, whereas
'T210000/T080000' identifies the range from 2100 until 0800 of
the following day.
When a range spans midnight, by definition it includes parts
of two successive days. When one of these days is also
selected by either the MonthOfYearMask, DayOfMonthMask, and/or
DayOfWeekMask, but the other day is not, then the policy is
active only during the portion of the range that falls on the
selected day. For example, if the range extends from 2100
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until 0800, and the day of week mask selects Monday and
Tuesday, then the policy is active during the following three
intervals:
From midnight Sunday until 0800 Monday
From 2100 Monday until 0800 Tuesday
From 2100 Tuesday until 23:59:59 Tuesday
Setting this value to 'T000000/T235959' will cause the
schedule to act independently of the time of day."
DEFVAL { '543030303030302F54323335393539'H } -- T000000/T235959
::= { pmSchedEntry 8 }
pmSchedLocalOrUtc OBJECT-TYPE
SYNTAX INTEGER {
localTime(1),
utcTime(2)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object indicates whether the times represented in the
TimePeriod object and in the various Mask objects represent
local times or UTC times."
DEFVAL { utcTime }
::= { pmSchedEntry 9 }
pmSchedStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object defines whether this schedule entry is kept
in volatile storage and lost upon reboot or
backed up by non-volatile or permanent storage.
Conceptual rows having the value 'permanent' must allow write
access to the columnar objects pmSchedDescr, pmSchedWeekDay,
pmSchedMonth, and pmSchedDay.
If the value of this object is 'permanent', no values in the
associated row have to be writable."
DEFVAL { volatile }
::= { pmSchedEntry 10 }
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pmSchedRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this schedule entry.
If the value of this object is active, no object in this row
may be modified."
::= { pmSchedEntry 11 }
-- Policy Tracking
-- The "policy to element" (PE) table and the "element to policy" (EP)
-- table track the status of execution contexts grouped by policy and
-- element respectively.
pmTrackingPETable OBJECT-TYPE
SYNTAX SEQUENCE OF PmTrackingPEEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The pmTrackingPETable describes what elements
are active (under control of) a policy. This table is indexed
in order to optimize retrieval of the entire status for a
given policy."
::= { pmMib 9 }
pmTrackingPEEntry OBJECT-TYPE
SYNTAX PmTrackingPEEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in the pmTrackingPETable. The pmPolicyIndex in
the index specifies the policy tracked by this entry.
Note that some combinations of index values may result in an
instance name that exceeds a length of 128 sub-identifiers,
which exceeds the maximum for the SNMP
protocol. Implementations should take care to avoid such
combinations."
INDEX { pmPolicyIndex, pmTrackingPEElement,
pmTrackingPEContextName, pmTrackingPEContextEngineID }
::= { pmTrackingPETable 1 }
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PmTrackingPEEntry ::= SEQUENCE {
pmTrackingPEElement RowPointer,
pmTrackingPEContextName SnmpAdminString,
pmTrackingPEContextEngineID OCTET STRING,
pmTrackingPEInfo BITS
}
pmTrackingPEElement OBJECT-TYPE
SYNTAX RowPointer
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The element that is acted upon by the associated policy.
As this object is used in the index for the
pmTrackingPETable, users of this table should be careful not
to create entries that would result in instance names with
more than 128 sub-identifiers."
::= { pmTrackingPEEntry 1 }
pmTrackingPEContextName OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE (0..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is not in the default SNMP context
for the target system, this object is used to identify the
context. If the element is in the default context, this object
is equal to the empty string."
::= { pmTrackingPEEntry 2 }
pmTrackingPEContextEngineID OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (0 | 5..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is on a remote system, this object
is used to identify the remote system. This object contains
the contextEngineID of the system on which the associated
element resides. If the element is on the local system,
this object will be the empty string."
::= { pmTrackingPEEntry 3 }
pmTrackingPEInfo OBJECT-TYPE
SYNTAX BITS {
actionSkippedDueToPrecedence(0),
conditionRunTimeException(1),
conditionUserSignal(2),
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actionRunTimeException(3),
actionUserSignal(4)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"This object returns information about the previous policy
script executions.
If the actionSkippedDueToPrecedence(1) bit is set, the last
execution of the associated policy condition returned non-zero,
but the action is not active, because it was trumped by a
matching policy condition in the same precedence group with a
higher precedence value.
If the conditionRunTimeException(2) bit is set, the last
execution of the associated policy condition encountered a
run-time exception and aborted.
If the conditionUserSignal(3) bit is set, the last
execution of the associated policy condition called the
signalError() function.
If the actionRunTimeException(4) bit is set, the last
execution of the associated policy action encountered a
run-time exception and aborted.
If the actionUserSignal(5) bit is set, the last
execution of the associated policy action called the
signalError() function.
Entries will only exist in this table of one or more bits are
set. In particular, if an entry does not exist for a
particular policy/element combination, it can be assumed that
the policy's condition did not match 'this element'."
::= { pmTrackingPEEntry 4 }
-- Element to Policy Table
pmTrackingEPTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmTrackingEPEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The pmTrackingEPTable describes what policies
are controlling an element. This table is indexed in
order to optimize retrieval of the status of all policies
active for a given element."
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::= { pmMib 10 }
pmTrackingEPEntry OBJECT-TYPE
SYNTAX PmTrackingEPEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in the pmTrackingEPTable. Entries exist for all
element/policy combinations for which the policy's condition
matches and only if the schedule for the policy is active.
The pmPolicyIndex in the index specifies the policy
tracked by this entry.
Note that some combinations of index values may result in an
instance name that exceeds a length of 128 sub-identifiers,
which exceeds the maximum for the SNMP protocol.
Implementations should take care to avoid such combinations."
INDEX { pmTrackingEPElement, pmTrackingEPContextName,
pmTrackingEPContextEngineID, pmPolicyIndex }
::= { pmTrackingEPTable 1 }
PmTrackingEPEntry ::= SEQUENCE {
pmTrackingEPElement RowPointer,
pmTrackingEPContextName SnmpAdminString,
pmTrackingEPContextEngineID OCTET STRING,
pmTrackingEPStatus INTEGER
}
pmTrackingEPElement OBJECT-TYPE
SYNTAX RowPointer
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The element acted upon by the associated policy.
As this object is used in the index for the
pmTrackingEPTable, users of this table should be careful
not to create entries that would result in instance names
with more than 128 sub-identifiers."
::= { pmTrackingEPEntry 1 }
pmTrackingEPContextName OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE (0..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is not in the default SNMP context
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for the target system, this object is used to identify the
context. If the element is in the default context, this object
is equal to the empty string."
::= { pmTrackingEPEntry 2 }
pmTrackingEPContextEngineID OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (0 | 5..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is on a remote system, this object
is used to identify the remote system. This object contains
the contextEngineID of the system on which the associated
element resides. If the element is on the local system,
this object will be the empty string."
::= { pmTrackingEPEntry 3 }
pmTrackingEPStatus OBJECT-TYPE
SYNTAX INTEGER {
on(1),
forceOff(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This entry will only exist if the calendar for the policy is
active and if the associated policyCondition returned 1 for
'this element'.
A policy can be forcibly disabled on a particular element
by setting this value to forceOff(2). The agent should then
act as though the policyCondition failed for 'this element'.
The forceOff(2) state will persist (even across reboots) until
this value is set to on(1) by a management request. The
forceOff(2) state may be set even if the entry does not
previously exist so that future policy invocations can be
avoided.
Unless forcibly disabled, if this entry exists, its value
will be on(1)."
::= { pmTrackingEPEntry 4 }
-- Policy Debugging Table
pmDebuggingTable OBJECT-TYPE
SYNTAX SEQUENCE OF PmDebuggingEntry
MAX-ACCESS not-accessible
STATUS current
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DESCRIPTION
"Policies that have debugging turned on will generate a log
entry in the policy debugging table for every runtime
exception that occurs in either the condition or action
code.
The pmDebuggingTable logs debugging messages when
policies experience run-time exceptions in either the condition
or action code and the associated pmPolicyDebugging object
has been turned on.
The maximum number of debugging entries that will be stored
and the maximum length of time an entry will be kept are an
implementation-dependent manner. If entries must
be discarded to make room for new entries, the oldest entries
must be discarded first.
If the system restarts, all debugging entries may be deleted."
::= { pmMib 11 }
pmDebuggingEntry OBJECT-TYPE
SYNTAX PmDebuggingEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in the pmDebuggingTable. The pmPolicyIndex in the
index specifies the policy that encountered the exception
that led to this log entry.
Note that some combinations of index values may result in an
instance name that exceeds a length of 128 sub-identifiers,
which exceeds the maximum for the SNMP protocol.
Implementations should take care to avoid such combinations."
INDEX { pmPolicyIndex, pmDebuggingElement,
pmDebuggingContextName, pmDebuggingContextEngineID,
pmDebuggingLogIndex }
::= { pmDebuggingTable 1 }
PmDebuggingEntry ::= SEQUENCE {
pmDebuggingElement RowPointer,
pmDebuggingContextName SnmpAdminString,
pmDebuggingContextEngineID OCTET STRING,
pmDebuggingLogIndex Unsigned32,
pmDebuggingMessage PmUTF8String
}
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pmDebuggingElement OBJECT-TYPE
SYNTAX RowPointer
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The element the policy was executing on when it encountered
the error that led to this log entry.
For example, if the element is interface 3, then this object
will contain the OID for 'ifIndex.3'.
As this object is used in the index for the
pmDebuggingTable, users of this table should be careful
not to create entries that would result in instance names
with more than 128 sub-identifiers."
::= { pmDebuggingEntry 1 }
pmDebuggingContextName OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE (0..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is not in the default SNMP context
for the target system, this object is used to identify the
context. If the element is in the default context, this object
is equal to the empty string."
::= { pmDebuggingEntry 2 }
pmDebuggingContextEngineID OBJECT-TYPE
SYNTAX OCTET STRING (SIZE (0 | 5..32))
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"If the associated element is on a remote system, this object
is used to identify the remote system. This object contains
the contextEngineID of the system on which the associated
element resides. If the element is on the local system,
this object will be the empty string."
::= { pmDebuggingEntry 3 }
pmDebuggingLogIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A unique index for this log entry among other log entries
for this policy/element combination."
::= { pmDebuggingEntry 4 }
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pmDebuggingMessage OBJECT-TYPE
SYNTAX PmUTF8String (SIZE (0..128))
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An error message generated by the policy execution
environment. It is recommended that this message include the
time of day when the message was generated, if known."
::= { pmDebuggingEntry 5 }
-- Notifications
pmNotifications OBJECT IDENTIFIER ::= { pmMib 0 }
pmNewRoleNotification NOTIFICATION-TYPE
OBJECTS { pmRoleStatus }
STATUS current
DESCRIPTION
"The pmNewRoleNotification is sent when an agent is configured
with its first instance of a previously unused role string
(not every time a new element is given a particular role).
An instance of the pmRoleStatus object is sent containing
the new roleString in its index. In the event that two or
more elements are given the same role simultaneously, it is an
implementation-dependent matter as to which pmRoleTable
instance will be included in the notification."
::= { pmNotifications 1 }
pmNewCapabilityNotification NOTIFICATION-TYPE
OBJECTS { pmCapabilitiesType }
STATUS current
DESCRIPTION
"The pmNewCapabilityNotification is sent when an agent
gains a new capability that did not previously exist in any
element on the system (not every time an element gains a
particular capability).
An instance of the pmCapabilitiesType object is sent containing
the identity of the new capability. In the event that two or
more elements gain the same capability simultaneously, it is an
implementation-dependent matter as to which pmCapabilitiesType
instance will be included in the notification."
::= { pmNotifications 2 }
pmAbnormalTermNotification NOTIFICATION-TYPE
OBJECTS { pmTrackingPEInfo }
STATUS current
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DESCRIPTION
"The pmAbnormalTermNotification is sent when a policy's
pmPolicyAbnormalTerminations gauge value changes from zero to
any value greater than zero and no such notification has been
sent for that policy in the last 5 minutes.
The notification contains an instance of the pmTrackingPEInfo
object where the pmPolicyIndex component of the index
identifies the associated policy and the rest of the index
identifies an element on which the policy failed."
::= { pmNotifications 3 }
-- Compliance Statements
pmConformance OBJECT IDENTIFIER ::= { pmMib 12 }
pmCompliances OBJECT IDENTIFIER ::= { pmConformance 1 }
pmGroups OBJECT IDENTIFIER ::= { pmConformance 2 }
pmCompliance MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"Describes the requirements for conformance to
the Policy-Based Management MIB"
MODULE -- this module
MANDATORY-GROUPS { pmPolicyManagementGroup, pmSchedGroup,
pmNotificationGroup }
::= { pmCompliances 1 }
pmPolicyManagementGroup OBJECT-GROUP
OBJECTS { pmPolicyPrecedenceGroup, pmPolicyPrecedence,
pmPolicySchedule, pmPolicyElementTypeFilter,
pmPolicyConditionScriptIndex, pmPolicyActionScriptIndex,
pmPolicyParameters,
pmPolicyConditionMaxLatency, pmPolicyActionMaxLatency,
pmPolicyMaxIterations,
pmPolicyDescription, pmPolicyMatches,
pmPolicyAbnormalTerminations,
pmPolicyExecutionErrors, pmPolicyDebugging,
pmPolicyStorageType, pmPolicyAdminStatus,
pmPolicyRowStatus, pmPolicyCodeText, pmPolicyCodeStatus,
pmElementTypeRegMaxLatency, pmElementTypeRegDescription,
pmElementTypeRegStorageType, pmElementTypeRegRowStatus,
pmRoleStatus,
pmCapabilitiesType, pmCapabilitiesOverrideState,
pmCapabilitiesOverrideRowStatus,
pmTrackingPEInfo,
pmTrackingEPStatus,
pmDebuggingMessage }
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RFC 4011 Policy Based Management MIB March 2005
STATUS current
DESCRIPTION
"Objects that allow for the creation and management of
configuration policies."
::= { pmGroups 1 }
pmSchedGroup OBJECT-GROUP
OBJECTS { pmSchedLocalTime, pmSchedGroupIndex,
pmSchedDescr, pmSchedTimePeriod,
pmSchedMonth, pmSchedDay, pmSchedWeekDay,
pmSchedTimeOfDay, pmSchedLocalOrUtc, pmSchedStorageType,
pmSchedRowStatus
}
STATUS current
DESCRIPTION
"Objects that allow for the scheduling of policies."
::= { pmGroups 2 }
pmNotificationGroup NOTIFICATION-GROUP
NOTIFICATIONS { pmNewRoleNotification,
pmNewCapabilityNotification,
pmAbnormalTermNotification }
STATUS current
DESCRIPTION
"Notifications sent by an Policy MIB agent."
::= { pmGroups 3 }
pmBaseFunctionLibrary OBJECT IDENTIFIER ::= { pmGroups 4 }
END
12. Relationship to Other MIB Modules
When policy-based management is used specifically for (policy-based)
configuration, the "Configuring Networks and Devices With SNMP" RFC
3512 [19] document describes configuration management practices,
terminology, and an example of a MIB Module that may be helpful to
those developing and using this technology.
The Policy MIB accesses system instrumentation for the purposes of
policy evaluation, control, notification, monitoring, and error
reporting. This information is available to managers in the form of
MIB objects. Information about system configuration is modified by
the Policy MIB through MIB objects defined in other MIB Modules.
Details about the operational or configuration details of a system
are retrieved by the manager via access to the specific MIB objects
available in a network element. As such, the Policy MIB can use any
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RFC 4011 Policy Based Management MIB March 2005
standard or vendor-defined object that exists on a managed system.
In particular, the Policy MIB may access standard or vendor specific
objects that are instance-specific such as BGP timeout parameters and
specific interface counters.
13. Security Considerations
This MIB contains no objects for which read access would disclose
sensitive information.
There are a number of management objects defined in this MIB that
have a MAX-ACCESS clause of read-write and/or read-create. Such
objects may be considered sensitive or vulnerable in some network
environments. The support for SET operations in a non-secure
environment without proper protection can have a negative effect on
network operations.
With the exception of pmPolicyDescription, pmPolicyDebugging,
pmElementTypeRegDescription, and pmSchedDescr, EVERY read-create and
read-write object in this MIB should be considered sensitive because
if an unauthorized user could manipulate these objects, s/he could
cause the Policy MIB system to use the stored credentials of an
authorized user to perform unauthorized and potentially harmful
operations.
There are no read-only objects in this MIB that contain sensitive
information.
SNMP versions prior to SNMPv3 did not include adequate security.
Even if the network itself is secure (for example by using IPSec),
even then, there is no control as to who on the secure network is
allowed to access and GET/SET (read/change/create/delete) the objects
in this MIB module.
It is RECOMMENDED that implementers consider the security features as
provided by the SNMPv3 framework (see [16], section 8), including
full support for the SNMPv3 cryptographic mechanisms (for
authentication and privacy).
Further, deployment of SNMP versions prior to SNMPv3 is NOT
RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to
enable cryptographic security. It is then a customer/operator
responsibility to ensure that the SNMP entity giving access to an
instance of this MIB module is properly configured to give access to
the objects only to those principals (users) that have legitimate
rights to indeed GET or SET (change/create/delete) them.
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An implementation must ensure that access control rules are applied
when SNMP operations are performed in policy scripts. To ensure
this, an implementation must record and maintain the security
credentials of the last entity to modify each policy's
pmPolicyAdminStatus object. The credentials to store are the
securityModel, securityName, and securityLevel and will be used as
input parameters for isAccessAllowed from the Architecture for
Describing SNMP Management Frameworks [1]. This mechanism was first
introduced in the DISMAN-SCHEDULE-MIB [12].
SNMP requests made when secModel, secName, and secLevel are specified
use credentials stored in the local configuration datastore. Access
to these credentials depends on the security credentials of the last
entity to modify the policy's pmPolicyAdminStatus object. To
determine whether the credentials can be accessed, the
isAccessAllowed abstract service interface defined in RFC 3411 [1] is
called:
statusInformation = -- success or errorIndication
isAccessAllowed(
IN securityModel -- Security Model used
IN securityName -- principal who wants to access
IN securityLevel -- Level of Security used
IN viewType -- write
IN contextName -- context containing variableName
IN variableName -- OID for an object in the proper
-- LCD entry
)
The securityModel, securityName, and securityLevel parameters are
set to the values that were recorded when the policy was modified.
The viewType is set to write, and the contextName and variableName
are set to select any read-create object in the appropriate LCD
entry.
Proper configuration of VACM requires that write access to an LCD
entry not be given to entities that aren't authorized to use the
credentials therein.
Access control for SNMP requests made to the local system where
secModel, secName, and secLevel aren't specified depends on the
security credentials of the last entity to modify the policy's
pmPolicyAdminStatus object. To determine whether the operation
should succeed, the isAccessAllowed abstract service interface
defined in RFC 3411 [1] is called:
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RFC 4011 Policy Based Management MIB March 2005
statusInformation = -- success or errorIndication
isAccessAllowed(
IN securityModel -- Security Model in use
IN securityName -- principal who wants to access
IN securityLevel -- Level of Security
IN viewType -- read, write, or notify view
IN contextName -- context as specified
IN variableName -- OID for the managed object
)
The securityModel, securityName, and securityLevel parameters are
set to the values that were recorded when the policy was modified.
The viewType, contextName, and variableName parameters are set as
appropriate for the requested SNMP operation.
Unless all users who have write access to the pmPolicyTable and
pmPolicyCodeTable have equivalent access to the managed system,
policy scripts could be used by a user to gain the privileges of
another user. Therefore, when policy users have different access,
access control should be applied so that a user's policies cannot be
modified by another user. To make this more convenient, a user can
place all of his or her policies in the same pmPolicyAdminGroup so
that a single access control view can apply to all of them.
Some policies may be designed to ensure the security of a network.
If these policies have not been installed pending the appearance of a
role or capability, some delay will occur in their activation
policies when the role or capability appears because a responsible
manager must notice the change and install the policy. This delay
may expose the device or the network to unacceptable security
vulnerabilities during this delay. If the role or capability appears
during a time of network stress or when the management station is
unavailable, this delay could be extensive, further increasing the
exposure. It is recommended that management stations install any
security-related policies that might ever be needed on a particular
managed device, even if a nonexistent role or capability suggests
that it is not needed at a given time.
This MIB allows the delegation of access rights so that a user
("Joe") can instruct a Policy MIB agent to execute remote operations
on his behalf that are authorized by keys stored by "Joe" into the
usmUserTable. Care needs to be taken to ensure that unauthorized
users are unable to configure their policies to use Joe's keys.
Although there are theoretically many ways to configure SNMP
security, users are advised to follow the most straightforward way
outlined below to minimize complexity and the resulting opportunity
for errors.
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RFC 4011 Policy Based Management MIB March 2005
Assume that Joe has credentials that give him authority to manage
agents A, B, and C, as well as the Policy MIB agent "P". Joe will
store credentials for Joe@A, Joe@B, and Joe@C in the usmUserTable
of the Policy MIB agent. Then the following VACM configuration
will be used:
VACM securityToGroupTable
A single entry mapping user Joe@P to group JoesGroup
VACM accessTable
A single entry mapping group JoesGroup to write view JoesView
VACM viewTreeFamilyTable
ViewName Subtree Type
JoesView points to Joe@A in usmUserTable included
JoesView points to Joe@B in usmUserTable included
JoesView points to Joe@C in usmUserTable included
In the preceding examples, the notation Joe@A represents the entry
indexed by usmUserEngineID and usmUserName, where the SnmpEngineID
is that of system A and the usmUserName is "Joe".
14. IANA Considerations
This is a profile of stringprep. It has been registered by the IANA
in the stringprep profile registry located at:
http://www.iana.org/assignments/stringprep-profiles
Name of this profile:
Policy MIB Stringprep.
RFC in which the profile is defined:
This document.
Indicator whether this is the newest version of the profile:
This is the first version of Policy MIB Stringprep.
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15. Acknowledgements
The authors gratefully acknowledge the significant contributions to
this work made by Jeff Case, Patrik Falstrom, Joel Halpern, Pablo
Halpern, Bob Moore, Steve Moulton, David Partain, and Walter Weiss.
This MIB uses a security delegation mechanism that was first
introduced in the DISMAN-SCHEDULE-MIB [12]. The Schedule table of
this MIB borrows heavily from the PolicyTimePeriodCondition of the
Policy Core Information Model (PCIM) [18] and from the DISMAN-
SCHEDULE-MIB [12].
16. References
16.1. Normative References
[1] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for
Describing Simple Network Management Protocol (SNMP) Management
Frameworks", STD 62, RFC 3411, December 2002.
[2] McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Structure of
Management Information Version 2 (SMIv2)", STD 58, RFC 2578,
April 1999.
[3] McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Textual
Conventions for SMIv2", STD 58, RFC 2579, April 1999.
[4] McCloghrie, K., Perkins, D., and J. Schoenwaelder, "Conformance
Statements for SMIv2", STD 58, RFC 2580, April 1999.
[5] Presuhn, R., "Transport Mappings for the Simple Network
Management Protocol (SNMP)", STD 62, RFC 3417, December 2002.
[6] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM)
for version 3 of the Simple Network Management Protocol
(SNMPv3)", STD 62, RFC 3414, December 2002.
[7] Presuhn, R., "Version 2 of the Protocol Operations for the
Simple Network Management Protocol (SNMP)", STD 62, RFC 3416,
December 2002.
[8] Frye, R., Levi, D., Routhier, S., and B. Wijnen, "Coexistence
between Version 1, Version 2, and Version 3 of the Internet-
standard Network Management Framework", BCP 74, RFC 3584, August
2003.
Waldbusser, et al. Standards Track [Page 118]
RFC 4011 Policy Based Management MIB March 2005
[9] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access
Control Model (VACM) for the Simple Network Management Protocol
(SNMP)", STD 62, RFC 3415, December 2002.
[10] International Standards Organization, "Information Technology -
Programming Languages - C++", ISO/IEC 14882-1998
[11] Daniele, M. and J. Schoenwaelder, "Textual Conventions for
Transport Addresses", RFC 3419, December 2002.
[12] Levi, D. and J. Schoenwaelder, "Definitions of Managed Objects
for Scheduling Management Operations", RFC 3231, January 2002.
[13] Hoffman, P. and M. Blanchet, "Preparation of Internationalized
Strings ("stringprep")", RFC 3454, December 2002.
[14] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD
63, RFC 3629, November 2003.
[15] Dawson, F. and D. Stenerson, "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)", RFC 2445,
November 1998.
16.2. Informative References
[16] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction
and Applicability Statements for Internet-Standard Management
Framework", RFC 3410, December 2002.
[17] ECMA, "ECMAScript Language Specification", ECMA-262, December
1999
[18] Moore, B., Ellesson, E., Strassner, J., and A. Westerinen,
"Policy Core Information Model -- Version 1 Specification", RFC
3060, February 2001.
[19] MacFaden, M., Partain, D., Saperia, J., and W. Tackabury,
"Configuring Networks and Devices with Simple Network Management
Protocol (SNMP)", RFC 3512, April 2003.
Waldbusser, et al. Standards Track [Page 119]
RFC 4011 Policy Based Management MIB March 2005
Author's Addresses
Steve Waldbusser
Phone: +1-650-948-6500
Fax: +1-650-745-0671
EMail: waldbusser@nextbeacon.com
Jon Saperia (WG Co-chair)
JDS Consulting, Inc.
84 Kettell Plain Road.
Stow MA 01775
USA
Phone: +1-978-461--0249
Fax: +1-617-249-0874
EMail: saperia@jdscons.com
Thippanna Hongal
Riverstone Networks, Inc.
5200 Great America Parkway
Santa Clara, CA, 95054
USA
Phone: +1-408-878-6562
Fax: +1-408-878-6501
EMail: hongal@riverstonenet.com
Waldbusser, et al. Standards Track [Page 120]
RFC 4011 Policy Based Management MIB March 2005
Full Copyright Statement
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contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
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Waldbusser, et al. Standards Track [Page 121]
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