Network Working Group M. Daniele
Request for Comments: 2257 Digital Equipment Corporation
Category: Standards Track B. Wijnen
T.J. Watson Research Center, IBM Corp.
D. Francisco, Ed.
Cisco Systems, Inc.
January 1998
Agent Extensibility (AgentX) Protocol
Version 1
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 (1998). All Rights Reserved.
Table of Contents
1 IntrodUCtion......................................................4
2 The SNMP Framework................................................4
2.1 A Note on Terminology.........................................4
3 Extending the MIB.................................................5
3.1 Motivation for AgentX.........................................5
4 AgentX Framework..................................................6
4.1 AgentX Roles..................................................7
4.2 Applicability.................................................8
4.3 Design Features of AgentX.....................................9
4.4 Non-Goals....................................................10
5 AgentX Encodings.................................................10
5.1 Object Identifier............................................11
5.2 SearchRange..................................................13
5.3 Octet String.................................................14
5.4 Value Representation.........................................14
6 Protocol Definitions.............................................16
6.1 AgentX PDU Header............................................16
6.1.1 Context..................................................19
6.2 AgentX PDUs..................................................20
6.2.1 The agentx-Open-PDU......................................20
6.2.2 The agentx-Close-PDU.....................................21
6.2.3 The agentx-Register-PDU..................................22
6.2.4 The agentx-Unregister-PDU................................25
6.2.5 The agentx-Get-PDU.......................................27
6.2.6 The agentx-GetNext-PDU...................................29
6.2.7 The agentx-GetBulk-PDU...................................30
6.2.8 The agentx-TestSet-PDU...................................31
6.2.9 The agentx-CommitSet, -UndoSet, -CleanupSet
PDUs.....................................................33
6.2.10 The agentx-Notify-PDU...................................33
6.2.11 The agentx-Ping-PDU.....................................34
6.2.12 The agentx-IndexAllocate-PDU............................35
6.2.13 The agentx-IndexDeallocate-PDU..........................36
6.2.14 The agentx-AddAgentCaps-PDU.............................37
6.2.15 The agentx-RemoveAgentCaps-PDU..........................38
6.2.16 The agentx-Response-PDU.................................39
7 Elements of Procedure............................................41
7.1 Processing AgentX Administrative Messages....................42
7.1.1 Processing the agentx-Open-PDU...........................42
7.1.2 Processing the agentx-IndexAllocate-PDU..................43
7.1.3 Using the agentx-IndexAllocate-PDU.......................45
7.1.4 Processing the agentx-IndexDeallocate-PDU................47
7.1.5 Processing the agentx-Register-PDU.......................48
7.1.5.1 Handling Duplicate OID Ranges........................50
7.1.6 Processing the agentx-Unregister-PDU.....................51
7.1.7 Processing the agentx-AddAgentCaps-PDU...................51
7.1.8 Processing the agentx-RemoveAgentCaps-PDU................52
7.1.9 Processing the agentx-Close-PDU..........................52
7.1.10 Detecting Connection Loss...............................53
7.1.11 Processing the agentx-Notify-PDU........................53
7.1.12 Processing the agentx-Ping-PDU..........................54
7.2 Processing Received SNMP Protocol Messages...................54
7.2.1 Dispatching AgentX PDUs..................................55
7.2.1.1 agentx-Get-PDU.......................................57
7.2.1.2 agentx-GetNext-PDU...................................58
7.2.1.3 agentx-GetBulk-PDU...................................59
7.2.1.4 agentx-TestSet-PDU...................................60
7.2.1.5 Dispatch.............................................60
7.2.2 Subagent Processing of agentx-Get, GetNext,
GetBulk-PDUs.............................................61
7.2.2.1 Subagent Processing of the agentx-Get-PDU............61
7.2.2.2 Subagent Processing of the
agentx-GetNext-PDU...................................62
7.2.2.3 Subagent Processing of the
agentx-GetBulk-PDU...................................62
7.2.3 Subagent Processing of agentx-TestSet,
-CommitSet, -UndoSet, -CleanupSet-PDUs...................63
7.2.3.1 Subagent Processing of the
agentx-TestSet-PDU...................................64
7.2.3.2 Subagent Processing of the
agentx-CommitSet-PDU.................................65
7.2.3.3 Subagent Processing of the
agentx-UndoSet-PDU...................................65
7.2.3.4 Subagent Processing of the
agentx-CleanupSet-PDU................................65
7.2.4 Master Agent Processing of AgentX Responses..............66
7.2.4.1 Common Processing of All AgentX Response
PDUs.................................................66
7.2.4.2 Processing of Responses to agentx-Get-PDUs...........66
7.2.4.3 Processing of Responses to
agentx-GetNext-PDU and agentx-GetBulk-PDU............67
7.2.4.4 Processing of Responses to
agentx-TestSet-PDUs..................................68
7.2.4.5 Processing of Responses to
agentx-CommitSet-PDUs................................68
7.2.4.6 Processing of Responses to
agentx-UndoSet-PDUs..................................69
7.2.5 Sending the SNMP Response-PDU............................69
7.2.6 MIB Views................................................69
7.3 State Transitions............................................70
7.3.1 Set Transaction States...................................70
7.3.2 Transport Connection States..............................71
7.3.3 Session States...........................................73
8 Transport Mappings...............................................74
8.1 AgentX over TCP..............................................74
8.1.1 Well-known Values........................................74
8.1.2 Operation................................................74
8.2 AgentX over UNIX-domain Sockets..............................75
8.2.1 Well-known Values........................................75
8.2.2 Operation................................................75
9 Security Considerations..........................................76
10 Acknowledgements................................................77
11 Authors" and Editor"s Addresses.................................77
12 References......................................................78
13 Full Copyright Statement........................................80
1. Introduction
This memo defines a standardized framework for extensible SNMP
agents. It defines processing entities called master agents and
subagents, a protocol (AgentX) used to communicate between them, and
the elements of procedure by which the extensible agent processes
SNMP protocol messages.
2. The SNMP Framework
A management system contains: several (potentially many) nodes, each
with a processing entity, termed an agent, which has Access to
management instrumentation; at least one management station; and, a
management protocol, used to convey management information between
the agents and management stations. Operations of the protocol are
carried out under an administrative framework which defines
authentication, authorization, access control, and privacy policies.
Management stations execute management applications which monitor and
control managed elements. Managed elements are devices such as
hosts, routers, terminal servers, etc., which are monitored and
controlled via access to their management information.
Management information is viewed as a collection of managed objects,
residing in a virtual information store, termed the Management
Information Base (MIB). Collections of related objects are defined
in MIB modules. These modules are written using a subset of OSI"s
Abstract Syntax Notation One (ASN.1) [1], termed the Structure of
Management Information (SMI) (see RFC1902 [2]).
2.1. A Note on Terminology
The term "variable" refers to an instance of a non-aggregate object
type defined according to the conventions set forth in the SMI (RFC
1902, [2]) or the textual conventions based on the SMI (RFC1903
[3]). The term "variable binding" normally refers to the pairing of
the name of a variable and its associated value. However, if certain
kinds of exceptional conditions occur during processing of a
retrieval request, a variable binding will pair a name and an
indication of that exception.
A variable-binding list is a simple list of variable bindings.
The name of a variable is an OBJECT IDENTIFIER, which is the
concatenation of the OBJECT IDENTIFIER of the corresponding object
type together with an OBJECT IDENTIFIER fragment identifying the
instance. The OBJECT IDENTIFIER of the corresponding object-type is
called the OBJECT IDENTIFIER prefix of the variable. For the purpose
of eXPosition, the original Internet-standard
Network Management Framework, as described in RFCs 1155 (STD 16),
1157 (STD 15), and 1212 (STD 16), is termed the SNMP version 1
framework (SNMPv1). The current framework, as described in RFCs
1902-1908, is termed the SNMP version 2 framework (SNMPv2).
3. Extending the MIB
New MIB modules that extend the Internet-standard MIB are
continuously being defined by various IETF working groups. It is
also common for enterprises or individuals to create or extend
enterprise-specific or experimental MIBs.
As a result, managed devices are frequently complex collections of
manageable components that have been independently installed on a
managed node. Each component provides instrumentation for the
managed objects defined in the MIB module(s) it implements.
Neither the SNMP version 1 nor version 2 framework describes how the
set of managed objects supported by a particular agent may be changed
dynamically.
3.1. Motivation for AgentX
This very real need to dynamically extend the management objects
within a node has given rise to a variety of "extensible agents",
which typically comprise
- a "master" agent that is available on the standard transport
address and that accepts SNMP protocol messages
- a set of "subagents" that each contain management
instrumentation
- a protocol that operates between the master agent and subagents,
permitting subagents to "connect" to the master agent, and the
master agent to multiplex received SNMP protocol messages
amongst the subagents.
- a set of tools to aid subagent development, and a runtime (API)
environment that hides much of the protocol operation between a
subagent and the master agent.
The wide deployment of extensible SNMP agents, coupled with the lack
of Internet standards in this area, makes it difficult to field
SNMP-manageable applications. A vendor may have to support several
different subagent environments (APIs) in order to support different
target platforms.
It can also become quite cumbersome to configure subagents and
(possibly multiple) master agents on a particular managed node.
Specifying a standard protocol for agent extensibility (AgentX)
provides the technical foundation required to solve both of these
problems. Independently developed AgentX-capable master agents and
subagents will be able to interoperate at the protocol level.
Vendors can continue to differentiate their products in all other
respects.
4. AgentX Framework
Within the SNMP framework, a managed node contains a processing
entity, called an agent, which has access to management information.
Within the AgentX framework, an agent is further defined to consist
of
- a single processing entity called the master agent, which sends
and receives SNMP protocol messages in an agent role (as
specified by the SNMP version 1 and version 2 framework
documents) but typically has little or no direct access to
management information.
- 0 or more processing entities called subagents, which are
"shielded" from the SNMP protocol messages processed by the
master agent, but which have access to management information.
The master and subagent entities communicate via AgentX protocol
messages, as specified in this memo. Other interfaces (if any) on
these entities, and their associated protocols, are outside the scope
of this document. While some of the AgentX protocol messages appear
similar in syntax and semantics to the SNMP, bear in mind that AgentX
is not SNMP.
The internal operations of AgentX are invisible to an SNMP entity
operating in a manager role. From a manager"s point of view, an
extensible agent behaves exactly as would a non-extensible
(monolithic) agent that has access to the same management
instrumentation.
This transparency to managers is a fundamental requirement of AgentX,
and is what differentiates AgentX subagents from SNMP proxy agents.
4.1. AgentX Roles
An entity acting in a master agent role performs the following
functions:
- Accepts AgentX session establishment requests from subagents.
- Accepts registration of MIB regions by subagents.
- Sends and accepts SNMP protocol messages on the agent"s
specified transport addresses.
- Implements the agent role Elements of Procedure specified
for the administrative framework applicable to the SNMP protocol
message, except where they specify performing management
operations. (The application of MIB views, and the access
control policy for the managed node, are implemented by the
master agent.)
- Provides instrumentation for the MIB objects defined in RFC
1907 [5], and for any MIB objects relevant to any administrative
framework it supports.
- Sends and receives AgentX protocol messages to access
management information, based on the current registry of MIB
regions.
- Forwards notifications on behalf of subagents.
An entity acting in a subagent role performs the following functions:
- Initiates an AgentX session with the master agent.
- Registers MIB regions with the master agent.
- Instantiates managed objects.
- Binds OIDs within its registered MIB regions to actual
variables.
- Performs management operations on variables.
- Initiates notifications.
4.2 Applicability
It is intended that this memo specify the smallest amount of required
behavior necessary to achieve the largest benefit, that is, to cover
a very large number of possible MIB implementations and
configurations with minimum complexity and low "cost of entry".
This section discusses several typical usage scenarios.
1) Subagents implement separate MIB modules--for example,
subagent A implements "mib-2", subagent b implements "host-
resources".
It is anticipated that this will be the most common subagent
configuration.
2) Subagents implement rows in a "simple table". A simple table
is one in which row creation is not specified, and for which the
MIB does not define an object that counts entries in the table.
Examples of simple tables are rdbmsDBTable, udpTable, and
hrSWRunTable.
This is the most commonly defined type of MIB table, and probably
represents the next most typical configuration that AgentX would
support.
3) Subagents share MIBs along non-row partitions. Subagents
register "chunks" of the MIB that represent multiple rows, due to
the nature of the MIB"s index structure. Examples include
registering ipNetToMediaEntry.n, where n represents the ifIndex
value for an interface implemented by the subagent, and
tcpConnEntry.a.b.c.d, where a.b.c.d represents an IP address on an
interface implemented by the subagent.
AgentX supports these three common configurations, and all
permutations of them, completely. The consensus is that they
comprise a very large majority of current and likely future uses of
multi-vendor extensible agent configurations.
4) Subagents implement rows in "complex tables". Complex tables
here are defined as tables permitting row creation, or whose MIB
also defines an object that counts entries in the table. Examples
include the MIB-2 ifTable (due to ifNumber), and the RMON
historyControlTable.
The subagent that implements such a counter object (like ifNumber)
must go beyond AgentX to correctly implement it. This is an
implementation issue (and most new MIB designs no longer include such
objects).
To implement row creation in such tables, at least one AgentX
subagent must register at a point "higher" in the OID tree than an
individual row (per AgentX"s dispatching procedure). Again, this is
an implementation issue.
Scenarios in this category were thought to occur somewhat rarely in
configurations where subagents are independently implemented by
different vendors. The focus of a standard protocol, however, must
be in just those areas where multi- vendor interoperability must be
assured.
Note that it would be inefficient (due to AgentX registration
overhead) to share a table among AgentX subagents if the table
contains very dynamic instances, and each subagent registers fully
qualified instances. ipRouteTable could be an example of such a
table in some environments.
4.3. Design Features of AgentX
The primary features of the design described in this memo are:
1) A general architectural division of labor between master agent
and subagent: The master agent is MIB ignorant and SNMP
omniscient, while the subagent is SNMP ignorant and MIB omniscient
(for the MIB variables it instantiates). That is, master agents,
exclusively, are concerned with SNMP protocol operations and the
translations to and from AgentX protocol operations needed to
carry them out; subagents are exclusively concerned with
management instrumentation; and neither should intrude on the
other"s territory.
2) A standard protocol and "rules of engagement" to enable
interoperability between management instrumentation and extensible
agents.
3) Mechanisms for independently developed subagents to
integrate into the extensible agent on a particular managed node
in such a way that they need not be aware of any other existing
subagents.
4) A simple, deterministic registry and dispatching algorithm.
For a given extensible agent configuration, there is a single
subagent who is "authoritative" for any particular region of the
MIB (where "region" may extend from an entire MIB down to a single
object-instance).
5) Performance considerations. It is likely that the master
agent and all subagents will reside on the same host, and in such
cases AgentX is more a form of inter-process communication than a
traditional communications protocol.
Some of the design decisions made with this in mind include:
- 32-bit alignment of data within PDUs
- Native byte-order encoding by subagents
- Large AgentX PDU payload sizes.
4.4 Non-Goals
1) Subagent-to-subagent communication. This is out of scope,
due to the security ramifications and complexity involved.
2) Subagent access (via the master agent) to MIB variables.
This is not addressed, since various other mechanisms are
available and it was not a fundamental requirement.
3) The ability to accommodate every conceivable extensible
agent configuration option. This was the most contentious ASPect
in the development of this protocol. In essence, certain features
currently available in some commercial extensible agent products
are not included in AgentX. Although useful or even vital in some
implementation strategies, the rough consensus was that these
features were not appropriate for an Internet Standard, or not
typically required for independently developed subagents to
coexist. The set of supported extensible agent configurations is
described above, in Section 4.2.
Some possible future version of the AgentX protocol may provide
coverage for one or more of these "non-goals" or for new goals that
might be identified after greater deployment experience.
5. AgentX Encodings
AgentX PDUs consist of a common header, followed by PDU-specific data
of variable length. Unlike SNMP PDUs, AgentX PDUs are not encoded
using the BER (as specified in ISO 8824 [1]), but are transmitted as
a contiguous byte stream. The data within this stream is organized
to provide natural alignment with respect to the start of the PDU,
permitting direct (integer) access by the processing entities.
The first four fields in the header are single-byte values. A bit
(NETWORK_BYTE_ORDER) in the third field (h.flags) is used to indicate
the byte ordering of all multi-byte integer values in the PDU,
including those which follow in the header itself. This is described
in more detail in Section 6.1, "AgentX PDU Header", below.
PDUs are depicted in this memo using the following convention (where
byte 1 is the first transmitted byte):
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
byte 1 byte 2 byte 3 byte 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
byte 5 byte 6 byte 7 byte 8
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fields marked "<reserved>" are reserved for future use and must be
zero-filled.
5.1. Object Identifier
An object identifier is encoded as a 4-byte header, followed by a
variable number of contiguous 4-byte fields representing sub-
identifiers. This representation (termed Object Identifier) is as
follows:
Object Identifier
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix include <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Object Identifier header fields:
n_subid
The number (0-128) of sub-identifiers in the object identifier.
An ordered list of "n_subid" 4-byte sub-identifiers follows the
4-byte header.
prefix
An unsigned value used to reduce the length of object
identifier encodings. A non-zero value "x" is interpreted as
the first sub-identifier after "internet" (1.3.6.1), and
indicates an implicit prefix "internet.x" to the actual sub-
identifiers encoded in the Object Identifier. For example, a
prefix field value 2 indicates an implicit prefix "1.3.6.1.2".
A value of 0 in the prefix field indicates there is no prefix
to the sub-identifiers.
include
Used only when the Object Identifier is the start of a
SearchRange, as described in section 5.2.
A null Object Identifier consists of the 4-byte header with all bytes
set to 0.
Examples:
sysDescr.0 (1.3.6.1.2.1.1.1.0)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 2 0 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1.2.3.4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 0 0 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.2. SearchRange
A SearchRange consists of two Object Identifiers. In its
communication with a subagent, the master agent uses a SearchRange to
identify a requested variable binding, and, in GetNext and GetBulk
operations, to set an upper bound on the names of managed object
instances the subagent may send in reply.
The first Object Identifier in a SearchRange (called the starting
OID) indicates the beginning of the range. It is frequently (but not
necessarily) the name of a requested variable binding.
The "include" field in this OID"s header is a boolean value (0 or 1)
indicating whether or not the starting OID is included in the range.
The second object identifier indicates the non-inclusive end of the
range, and its "include" field is always 0.
Example: To indicate a search range from 1.3.6.1.2.1.25.2
(inclusive) to 1.3.6.1.2.1.25.2.1 (exclusive), the SearchRange would
be
(start)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3 2 1 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
25
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(end)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 2 0 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
25
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A SearchRangeList is a contiguous list of SearchRanges.
5.3. Octet String
An octet string is represented by a contiguous series of bytes,
beginning with a 4-byte integer whose value is the number of octets
in the octet string, followed by the octets themselves. This
representation is termed an Octet String. If the last octet does not
end on a 4-byte offset from the start of the Octet String, padding
bytes are appended to achieve alignment of following data. This
padding must be added even if the Octet String is the last item in
the PDU. Padding bytes must be zero filled.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A null Octet String consists of a 4-byte length field set to 0.
5.4. Value Representation
Variable bindings may be encoded within the variable-length portion
of some PDUs. The representation of a variable binding (termed a
VarBind) consists of a 2-byte type field, a name (Object Identifier),
and the actual value data.
VarBind
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
v.type <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(v.name)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(v.data)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
VarBind fields:
v.type
Indicates the variable binding"s syntax, and must be one of
the following values:
Integer (2),
Octet String (4),
Null (5),
Object Identifier (6),
IpAddress (64),
Counter32 (65),
Gauge32 (66),
TimeTicks (67),
Opaque (68),
Counter64 (70),
noSuchObject (128),
noSuchInstance (129),
endOfMibView (130)
v.name
The Object Identifier which names the variable.
v.data
The actual value, encoded as follows:
- Integer, Counter32, Gauge32, and TimeTicks are encoded as
4 contiguous bytes. If the NETWORK_BYTE_ORDER bit is set
in h.flags, the bytes are ordered most significant to least
significant, otherwise they are ordered least significant
to most significant.
- Counter64 is encoded as 8 contiguous bytes. If the
NETWORK_BYTE_ORDER bit is set in h.flags, the bytes are
ordered most significant to least significant, otherwise
they are ordered least significant to most significant.
- Object Identifiers are encoded as described in section
5.1, Object Identifier.
- IpAddress, Opaque, and Octet String are all octet strings
and are encoded as described in section 5.3, Octet String.
Value data always follows v.name whenever v.type is one
of the above types. These data bytes are present even if
they will not be used (as, for example, in certain types
of index allocation).
- Null, noSuchObject, noSuchInstance, and endOfMibView do not
contain any encoded value. Value data never follows
v.name in these cases.
Note that the VarBind itself does not contain the value size.
That information is implied for the fixed-length types, and
explicitly contained in the encodings of variable-length types
(Object Identifier and Octet String).
A VarBindList is a contiguous list of VarBinds. Within a
VarBindList, a particular VarBind is identified by an index value.
The first VarBind in a VarBindList has index value 1, the second
has index value 2, and so on.
6. Protocol Definitions
6.1. AgentX PDU Header
The AgentX PDU header is a fixed-format, 20-octet structure:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version h.type h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An AgentX PDU header contains the following fields:
h.version
The version of the AgentX protocol (1 for this memo).
h.type
The PDU type; one of the following values:
agentx-Open-PDU (1),
agentx-Close-PDU (2),
agentx-Register-PDU (3),
agentx-Unregister-PDU (4),
agentx-Get-PDU (5),
agentx-GetNext-PDU (6),
agentx-GetBulk-PDU (7),
agentx-TestSet-PDU (8),
agentx-CommitSet-PDU (9),
agentx-UndoSet-PDU (10),
agentx-CleanupSet-PDU (11),
agentx-Notify-PDU (12),
agentx-Ping-PDU (13),
agentx-IndexAllocate-PDU (14),
agentx-IndexDeallocate-PDU (15),
agentx-AddAgentCaps-PDU (16),
agentx-RemoveAgentCaps-PDU (17),
agentx-Response-PDU (18)
h.flags
A bitmask, with bit 0 the least significant bit. The bit
definitions are as follows:
Bit Definition
--- ----------
0 INSTANCE_REGISTRATION
1 NEW_INDEX
2 ANY_INDEX
3 NON_DEFAULT_CONTEXT
4 NETWORK_BYTE_ORDER
5-7 (reserved)
The NETWORK_BYTE_ORDER bit applies to all multi-byte integer
values in the entire AgentX packet, including the remaining
header fields. If set, then network byte order (most
significant byte first; "big endian") is used. If not set,
then least significant byte first ("little endian") is used.
The NETWORK_BYTE_ORDER bit applies to all AgentX PDUs.
The NON_DEFAULT_CONTEXT bit is used only in the AgentX PDUs
described in section 6.1.1.
The NEW_INDEX and ANY_INDEX bits are used only within the
agentx-IndexAllocate-, and -IndexDeallocate-PDUs.
The INSTANCE_REGISTRATION bit is used only within the agentx-
Register-PDU.
h.sessionID
The session ID uniquely identifies a session over which AgentX
PDUs are exchanged between a subagent and the master agent.
The session ID has no significance and no defined value in the
agentx-Open-PDU sent by a subagent to open a session with the
master agent; in this case, the master agent will assign a
unique sessionID that it will pass back in the corresponding
agentx-Response-PDU. From that point on, that same sessionID
will appear in every AgentX PDU exchanged over that session
between the master and the subagent. A subagent may establish
multiple AgentX sessions by sending multiple agentx-Open-PDUs
to the master agent.
In master agents that support multiple transport protocols, the
sessionID should be globally unique rather than unique just to
a particular transport.
h.transactionID
The transaction ID uniquely identifies, for a given session,
the single SNMP management request (and single SNMP PDU) with
which an AgentX PDU is associated. If a single SNMP management
request results in multiple AgentX PDUs being sent by the
master agent with the same sessionID, each of these AgentX PDUs
must contain the same transaction ID; conversely, AgentX PDUs
sent during a particular session, that result from distinct
SNMP management requests, must have distinct transaction IDs
within the limits of the 32-bit field).
Note that the transaction ID is not the same as the SNMP PDU"s
request-id (as described in section 4.1 of RFC1905 [4]), nor
can it be, since a master agent might receive SNMP requests
with the same request-ids from different managers.
The transaction ID has no significance and no defined value in
AgentX administrative PDUs, i.e., AgentX PDUs that are not
associated with an SNMP management request.
h.packetID
A packet ID generated by the sender for all AgentX PDUs except
the agentx-Response-PDU. In an agentx-Response-PDU, the packet
ID must be the same as that in the received AgentX PDU to which
it is a response. A master agent might use this field to
associate subagent response PDUs with their corresponding
request PDUs. A subagent might use this field to correlate
responses to multiple (batched) registrations.
h.payload_length
The size in octets of the PDU contents, excluding the 20-byte
header. As a result of the encoding schemes and PDU layouts,
this value will always be either 0, or a multiple of 4.
6.1.1. Context
In the SNMPv1 or v2c frameworks, the community string may be used as
an index into a local repository of configuration information that
may include community profiles or more complex context information.
Future versions of the SNMP will likely formalize this notion of
"context".
AgentX provides a mechanism for transmitting a context specification
within relevant PDUs, but does not place any constraints on the
content of that specification.
An optional context field may be present in the agentx-Register-,
UnRegister-, AddAgentCaps-, RemoveAgentCaps-, Get-, GetNext-,
GetBulk-, IndexAllocate-, IndexDeallocate-, Notify-, TestSet-, and
Ping- PDUs.
If the NON_DEFAULT_CONTEXT bit in the AgentX header field h.flags is
clear, then there is no context field in the PDU, and the operation
refers to the default context.
If the NON_DEFAULT_CONTEXT bit is set, then a context field
immediately follows the AgentX header, and the operation refers to
that specific context. The context is represented as an Octet
String. There are no constraints on its length or contents.
Thus, all of these AgentX PDUs (that is, those listed immediately
above) refer to, or "indicate" a context, which is either the default
context, or a non-default context explicitly named in the PDU.
6.2. AgentX PDUs
6.2.1. The agentx-Open-PDU
An agentx-Open-PDU is generated by a subagent to request
establishment of an AgentX session with the master agent.
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (1) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o.timeout <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(o.id)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
subidentifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
subidentifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(o.descr)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An agentx-Open-PDU contains the following fields:
o.timeout
The length of time, in seconds, that a master agent should
allow to elapse after dispatching a message to a subagent
before it regards the subagent as not responding. This is a
subagent-wide default value that may be overridden by values
associated with specific registered MIB regions. The default
value of 0 indicates that no subagent-wide value is requested.
o.id
An Object Identifier that identifies the subagent. Subagents
that do not support such an notion may send a null Object
Identifier.
o.descr
An Octet String containing a DisplayString describing the
subagent.
6.2.2. The agentx-Close-PDU
An agentx-Close-PDU issued by either a subagent or the master agent
terminates an AgentX session.
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (2) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
c.reason <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An agentx-Close-PDU contains the following field:
c.reason
An enumerated value that gives the reason that the master agent
or subagent closed the AgentX session. This field may take one
of the following values:
reasonOther(1)
None of the following reasons
reasonParseError(2)
Too many AgentX parse errors from peer
reasonProtocolError(3)
Too many AgentX protocol errors from peer
reasonTimeouts(4)
Too many timeouts waiting for peer
reasonShutdown(5)
Sending entity is shutting down
reasonByManager(6)
Due to Set operation; this reason code can be used only
by the master agent, in response to an SNMP management
request.
6.2.3. The agentx-Register-PDU
An agentx-Register-PDU is generated by a subagent for each region of
the MIB variable naming tree (within one or more contexts) that it
wishes to support.
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (3) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(r.context) (OPTIONAL)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
r.timeout r.priority r.range_subid <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(r.region)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(r.upper_bound)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
optional upper-bound sub-identifier
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An agentx-Register-PDU contains the following fields:
r.context
An optional non-default context.
r.timeout
The length of time, in seconds, that a master agent should
allow to elapse after dispatching a message to a subagent
before it regards the subagent as not responding. r.timeout
applies only to messages that concern MIB objects within
r.region. It overrides both the subagent-wide value (if any)
indicated when the AgentX session with the master agent was
established, and the master agent"s default timeout. The
default value for r.timeout is 0 (no override).
r.priority
A value between 1 and 255, used to achieve a desired
configuration when different subagents register identical or
overlapping regions. Subagents with no particular knowledge of
priority should register with the default value of 255 (lowest
priority).
In the master agent"s dispatching algorithm, smaller values of
r.priority take precedence over larger values, as described in
section 7.1.5.1.
r.region
An Object Identifier that, in conjunction with r.range_subid,
indicates a region of the MIB that a subagent wishes to
support. It may be a fully-qualified instance name, a partial
instance name, a MIB table, an entire MIB, or ranges of any of
these.
The choice of what to register is implementation-specific; this
memo does not specify permissible values. Standard practice
however is for a subagent to register at the highest level of
the naming tree that makes sense. Registration of fully-
qualified instances is typically done only when a subagent can
perform management operations only on particular rows of a
conceptual table.
If r.region is in fact a fully qualified instance name, the
INSTANCE_REGISTRATION bit in h.flags must be set, otherwise it
must be cleared. The master agent may save this information to
optimize subsequent operational dispatching.
r.range_subid
Permits specifying a range in place of one of r.region"s sub-
identifiers. If this value is 0, no range is specified.
Otherwise the "r.range_subid"-th sub-identifier in r.region is
a range lower bound, and the range upper bound sub-identifier
(r.upper_bound) immediately follows r.region.
This permits registering a conceptual row with a single PDU.
For example, the following PDU would register row 7 of the RFC
1573 ifTable (1.3.6.1.2.1.2.2.1.1-22.7):
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (3) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
r.timeout r.priority 5 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(r.region)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6 2 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(r.upper_bound)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
22
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
6.2.4. The agentx-Unregister-PDU
The agentx-Unregister-PDU is sent by a subagent to remove a
previously registered MIB region from the master agent"s OID space.
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (4) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(u.context) OPTIONAL
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
<reserved> u.priority u.range_subid <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(u.region)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(u.upper_bound)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
optional upper-bound sub-identifier
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An agentx-Unregister-PDU contains the following fields:
u.context
An optional non-default context.
u.priority
The priority at which this region was originally registered.
u.region
Indicates a previously-registered region of the MIB that a
subagent no longer wishes to support.
6.2.5. The agentx-Get-PDU
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (5) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(g.context) OPTIONAL
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(g.sr)
(start 1)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix include <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(end 1)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 0 0 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
(start n)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix include <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(end n)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 0 0 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An agentx-Get-PDU contains the following fields:
g.context
An optional non-default context.
g.sr
A SearchRangeList containing the requested variables for this
subagent.
6.2.6. The agentx-GetNext-PDU
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (6) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(g.context) OPTIONAL
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(g.sr)
(start 1)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix include <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(end 1)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
(start n)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix include <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(end n)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
6.2.7. The agentx-GetBulk-PDU
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (7) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(g.context) OPTIONAL
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
g.non_repeaters g.max_repetitions
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(g.sr) as in agentx-GetNext-PDU above
...
6.2.8. The agentx-TestSet-PDU
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (8) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(t.context) OPTIONAL
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(t.vb)
(VarBind 1)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
v.type <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
(VarBind n)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
v.type <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
n_subid prefix 0 <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
sub-identifier #n_subid
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
data
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An agentx-TestSet-PDU contains the following fields:
t.context
An optional non-default context.
t.vb
A VarBindList containing the requested VarBinds for this
subagent.
6.2.9. The agentx-CommitSet, -UndoSet, -CleanupSet PDUs
These PDUs consist of the AgentX header only.
The agentx-CommitSet-, -UndoSet-, and -Cleanup-PDUs are used in
processing an SNMP SetRequest operation.
6.2.10. The agentx-Notify-PDU
An agentx-Notify-PDU is sent by a subagent to cause the master agent
to forward a notification.
(AgentX header)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.version (1) h.type (12) h.flags <reserved>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.sessionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.transactionID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.packetID
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
h.payload_length
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(n.context) OPTIONAL
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet String Length (L)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet 1 Octet 2 Octet 3 Octet 4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Octet L - 1 Octet L Padding (as required)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(n.vb)
...
An agentx-Notify-PDU contains the following fields:
n.context
An optional non-default context.
n.vb
A VarBindList whose contents define the actual PDU to be sent.
This memo places the following restrictions on its contents:
- If the subagent supplies sysUpTime.0, it must be
present as the first varbind.
- snmpTrapOID.0 must be present, as the second
varbind if sysUpTime.0 was supplied, as the first if it
was not.
6.2.11 The agentx-Ping-PDU
The agentx-Ping-PDU is sent by a subagent to the master agent to
monitor the master agent"s ability to receive and send AgentX PDUs
over their AgentX session.
(AgentX header)
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