rfc1271.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                                      S. Waldbusser
Request for Comments: 1271                    Carnegie Mellon University
                                                           November 1991


         Remote Network Monitoring Management Information Base

Status of this Memo

   This memo is an extension to the SNMP MIB.  This RFC specifies an IAB
   standards track protocol for the Internet community, and requests
   discussion and suggestions for improvements.  Please refer to the
   current edition of the "IAB Official Protocol Standards" for the
   standardization state and status of this protocol.  Distribution of
   this memo is unlimited.

Table of Contents

   1. Abstract ..............................................    2
   2. The Network Management Framework.......................    2
   3. Objects ...............................................    2
   3.1 Format of Definitions ................................    3
   4. Overview ..............................................    3
   4.1 Remote Network Management Goals ......................    3
   4.2 Textual Conventions ..................................    5
   4.3 Structure of MIB .....................................    5
   4.3.1 The Statistics Group ...............................    6
   4.3.2 The History Group ..................................    6
   4.3.3 The Alarm Group ....................................    6
   4.3.4 The Host Group .....................................    6
   4.3.5 The HostTopN Group .................................    6
   4.3.6 The Matrix Group ...................................    7
   4.3.7 The Filter Group ...................................    7
   4.3.8 The Packet Capture Group ...........................    7
   4.3.9 The Event Group ....................................    7
   5. Control of Remote Network Monitoring Devices ..........    7
   5.1 Resource Sharing Among Multiple Management Stations ..    8
   5.2 Row Addition Among Multiple Management Stations ......    9
   6. Definitions ...........................................   10
   7. Acknowledgments .......................................   80
   8. References ............................................   80
   Security Considerations...................................   81
   Author's Address..........................................   81








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1.  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, it defines objects for managing remote network
   monitoring devices.

2.  The Network Management Framework

   The Internet-standard Network Management Framework consists of three
   components.  They are:

      RFC 1155 which defines the SMI, the mechanisms used for describing
      and naming objects for the purpose of management.  RFC 1212
      defines a more concise description mechanism, which is wholly
      consistent with the SMI.

      RFC 1156 which defines MIB-I, the core set of managed objects for
      the Internet suite of protocols.  RFC 1213, defines MIB-II, an
      evolution of MIB-I based on implementation experience and new
      operational requirements.

      RFC 1157 which defines the SNMP, the protocol used for network
      access to managed objects.

   The Framework permits new objects to be defined for the purpose of
   experimentation and evaluation.

3.  Objects

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the subset of Abstract Syntax Notation One (ASN.1) [7]
   defined in the SMI.  In particular, each object has a name, a syntax,
   and an encoding.  The name is an object identifier, an
   administratively assigned name, which specifies an object type.  The
   object type together with an object instance serves to uniquely
   identify a specific instantiation of the object.  For human
   convenience, we often use a textual string, termed the OBJECT
   DESCRIPTOR, to also refer to the object type.

   The syntax of an object type defines the abstract data structure
   corresponding to that object type.  The ASN.1 language is used for
   this purpose.  However, the SMI [3] purposely restricts the ASN.1
   constructs which may be used.  These restrictions are explicitly made
   for simplicity.

   The encoding of an object type is simply how that object type



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   is represented using the object type's syntax.  Implicitly
   tied to the notion of an object type's syntax and encoding is
   how the object type is represented when being transmitted on
   the network.

   The SMI specifies the use of the basic encoding rules of ASN.1 [8],
   subject to the additional requirements imposed by the SNMP.

3.1.  Format of Definitions

   Section 6 contains the specification of all object types
   contained in this MIB module.  The object types are defined
   using the conventions defined in the SMI, as amended by the
   extensions specified in [9,10].

4.  Overview

   Remote network monitoring devices are instruments that exist for the
   purpose of managing a network.  Often these remote probes are
   stand-alone devices and devote significant internal resources for the
   sole purpose of managing a network.  An organization may employ many
   of these devices, one per network segment, to manage its internet.  In
   addition, these devices may be used for a network management service
   provider to access a client network, often geographically remote.

   While many of the objects in this document are suitable for the
   management of any type of network, there are some which are specific
   to managing Ethernet networks.  The design of this MIB allows similar
   objects to be defined for other network types.  It is intended that
   future versions of this document will define extensions for other
   network types such as Token Ring and FDDI.

4.1.  Remote Network Management Goals

              o Offline Operation
                  There are sometimes conditions when a management
                  station will not be in constant contact with its
                  remote monitoring devices.  This is sometimes by
                  design in an attempt to lower communications costs
                  (especially when communicating over a WAN or
                  dialup link), or by accident as network failures
                  affect the communications between the management
                  station and the probe.

                  For this reason, this MIB allows a probe to be
                  configured to perform diagnostics and to collect
                  statistics continuously, even when communication with
                  the management station may not be possible or



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                  efficient.  The probe may then attempt to notify
                  the management station when an exceptional condition
                  occurs.  Thus, even in circumstances where
                  communication between management station and probe is
                  not continuous, fault, performance, and configuration
                  information may be continuously accumulated and
                  communicated to the management station conveniently
                  and efficiently.

              o Preemptive Monitoring
                  Given the resources available on the monitor, it
                  is potentially helpful for it continuously to run
                  diagnostics and to log network performance.  The
                  monitor is always available at the onset of any
                  failure.  It can notify the management station of the
                  failure and can store historical statistical
                  information about the failure.  This historical
                  information can be played back by the management
                  station in an attempt to perform further diagnosis
                  into the cause of the problem.

              o Problem Detection and Reporting
                  The monitor can be configured to recognize
                  conditions, most notably error conditions, and
                  continuously to check for them.  When one of these
                  conditions occurs, the event may be logged, and
                  management stations may be notified in a number of
                  ways.

              o Value Added Data
                  Because a remote monitoring device represents a
                  network resource dedicated exclusively to network
                  management functions, and because it is located
                  directly on the monitored portion of the network, the
                  remote network monitoring device has the opportunity
                  to add significant value to the data it collects.
                  For instance, by highlighting those hosts on the
                  network that generate the most traffic or errors, the
                  probe can give the management station precisely the
                  information it needs to solve a class of problems.

              o Multiple Managers
                  An organization may have multiple management stations
                  for different units of the organization, for different
                  functions (e.g. engineering and operations), and in an
                  attempt to provide disaster recovery.  Because
                  environments with multiple management stations are
                  common, the remote network monitoring device has to



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                  deal with more than own management station,
                  potentially using its resources concurrently.

4.2.  Textual Conventions

   Two new data types are introduced as a textual convention in this MIB
   document.  These textual conventions enhance the readability of the
   specification and can ease comparison with other specifications if
   appropriate.  It should be noted that the introduction of the these
   textual conventions has no effect on either the syntax nor the
   semantics of any managed objects.  The use of these is merely an
   artifact of the explanatory method used.  Objects defined in terms of
   one of these methods are always encoded by means of the rules that
   define the primitive type.  Hence, no changes to the SMI or the SNMP
   are necessary to accommodate these textual conventions which are
   adopted merely for the convenience of readers and writers in pursuit
   of the elusive goal of clear, concise, and unambiguous MIB documents.

   The new data types are: OwnerString and EntryStatus.

4.3.  Structure of MIB

   The objects are arranged into the following groups:

                  - statistics

                  - history

                  - alarm

                  - host

                  - hostTopN

                  - matrix

                  - filter

                  - packet capture

                  - event

   These groups are the basic unit of conformance.  If a remote
   monitoring device implements a group, then it must implement all
   objects in that group.  For example, a managed agent that implements
   the host group must implement the hostControlTable, the hostTable and
   the hostTimeTable.




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RFC 1271             Remote Network Monitoring MIB         November 1991


   All groups in this MIB are optional.  Implementations of this MIB
   must also implement the system and interfaces group of MIB-II [6].
   MIB-II may also mandate the implementation of additional groups.

   These groups are defined to provide a means of assigning object
   identifiers, and to provide a method for managed agents to know which
   objects they must implement.

4.3.1.  The Statistics Group

   The statistics group contains statistics measured by the probe for
   each monitored interface on this device.  This group currently
   consists of the etherStatsTable but in the future will contain tables
   for other media types including Token Ring and FDDI.

4.3.2.  The History Group

   The history group records periodic statistical samples from a network
   and stores them for later retrieval.  This group currently consists
   of the historyControlTable and the etherHistoryTable.  In future
   versions of the MIB, this group may contain tables for other media
   types including Token Ring and FDDI.

4.3.3.  The Alarm Group

   The alarm group periodically takes statistical samples from variables
   in the probe and compares them to previously configured thresholds.
   If the monitored variable crosses a threshold, an event is generated.
   A hysteresis mechanism is implemented to limit the generation of
   alarms.  This group consists of the alarmTable and requires the