rfc1493.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                                          E. Decker
Request for Comments: 1493                           cisco Systems, Inc.
Obsoletes: 1286                                              P. Langille
                                           Digital Equipment Corporation
                                                          A. Rijsinghani
                                           Digital Equipment Corporation
                                                           K. McCloghrie
                                                Hughes LAN Systems, Inc.
                                                               July 1993


                     Definitions of Managed Objects
                              for Bridges

Status of this Memo


   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.

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 MAC bridges based on
   the IEEE 802.1D-1990 standard between Local Area Network (LAN)
   segments.  Provisions are made for support of transparent bridging.
   Provisions are also made so that these objects apply to bridges
   connected by subnetworks other than LAN segments.

Table of Contents

   1. The Network Management Framework ......................    2
   2. Objects ...............................................    2
   2.1 Format of Definitions ................................    3
   3. Overview ..............................................    3
   3.1 Structure of MIB .....................................    3
   3.1.1 The dot1dBase Group ................................    6
   3.1.2 The dot1dStp Group .................................    6
   3.1.3 The dot1dSr Group ..................................    6
   3.1.4 The dot1dTp Group ..................................    6
   3.1.5 The dot1dStatic Group ..............................    6
   3.2 Relationship to Other MIBs ...........................    6
   3.2.1 Relationship to the 'system' group .................    6
   3.2.2 Relationship to the 'interfaces' group .............    7



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   3.3 Textual Conventions ..................................    8
   4. Changes from RFC 1286 .................................    8
   5. Definitions ...........................................    9
   5.1 Groups in the Bridge MIB .............................   11
   5.2 The dot1dBase Group Definitions ......................   11
   5.3 The dot1dStp Group Definitions .......................   14
   5.4 The dot1dTp Group Definitions ........................   22
   5.5 The dot1dStatic Group Definitions ....................   28
   5.6 Traps for use by Bridges .............................   31
   6. Acknowledgments .......................................   31
   7. References ............................................   33
   8. Security Considerations ...............................   33
   9. Authors' Addresses ....................................   34

1.  The Network Management Framework

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

      STD16/RFC 1155 which defines the SMI, the mechanisms used for
      describing and naming objects for the purpose of management.
      STD16/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.  STD17/RFC 1213, defines MIB-II,
      an evolution of MIB-I based on implementation experience and new
      operational requirements.

      STD15/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.

2.  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 is named by 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
   descriptor, to also refer to the object type.





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2.1.  Format of Definitions

   Section 5 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].

3.  Overview

   A common device present in many networks is the Bridge.  This device
   is used to connect Local Area Network segments below the network
   layer.

   There are two major modes defined for this bridging; transparent and
   source route.  The transparent method of bridging is defined in the
   draft IEEE 802.1d specification [11].  This memo defines those
   objects needed for the management of a bridging entity operating in
   the transparent mode, as well as some objects applicable to all types
   of bridges.

   To be consistent with IAB directives and good engineering practice,
   an explicit attempt was made to keep this MIB as simple as possible.
   This was accomplished by applying the following criteria to objects
   proposed for inclusion:

          (1)  Start with a small set of essential objects and add only
               as further objects are needed.

          (2)  Require objects be essential for either fault or
               configuration management.

          (3)  Consider evidence of current use and/or utility.

          (4)  Limit the total of objects.

          (5)  Exclude objects which are simply derivable from others in
               this or other MIBs.

          (6)  Avoid causing critical sections to be heavily
               instrumented.  The guideline that was followed is one
               counter per critical section per layer.

3.1.  Structure of MIB

   Objects in this MIB are arranged into groups.  Each group is
   organized as a set of related objects.  The overall structure and
   assignment of objects to their groups is shown below.  Where
   appropriate the corresponding IEEE 802.1d [11] management object name
   is also included.



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          Bridge MIB Name                  IEEE 802.1d Name

          dot1dBridge
            dot1dBase
              BridgeAddress                Bridge.BridgeAddress
              NumPorts                     Bridge.NumberOfPorts
              Type
              PortTable
                Port                       BridgePort.PortNumber
                IfIndex
                Circuit
                DelayExceededDiscards        .DiscardTransitDelay
                MtuExceededDiscards          .DiscardOnError
            dot1dStp
              ProtocolSpecification
              Priority                     SpanningTreeProtocol
                                             .BridgePriority
              TimeSinceTopologyChange        .TimeSinceTopologyChange
              TopChanges                     .TopologyChangeCount
              DesignatedRoot                 .DesignatedRoot
              RootCost                       .RootCost
              RootPort                       .RootPort
              MaxAge                         .MaxAge
              HelloTime                      .HelloTime
              HoldTime                       .HoldTime
              ForwardDelay                   .ForwardDelay
              BridgeMaxAge                   .BridgeMaxAge
              BridgeHelloTime                .BridgeHelloTime
              BridgeForwardDelay             .BridgeForwardDelay
              PortTable
                Port                        SpanningTreeProtocolPort
                                              .PortNumber
                Priority                      .PortPriority
                State                         .SpanningTreeState
                Enable
                PathCost                      .PortPathCost
                DesignatedRoot                .DesignatedRoot
                DesignatedCost                .DesignatedCost
                DesignatedBridge              .DesignatedBridge
                DesignatedPort                .DesignatedPort
                ForwardTransitions
            dot1dTp
              LearnedEntryDiscards          BridgeFilter.DatabaseSize
                                              .NumDynamic,NumStatic
              AgingTime                     BridgeFilter.AgingTime
              FdbTable
                Address
                Port



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                Status
              PortTable
                Port
                MaxInfo
                InFrames                    BridgePort.FramesReceived
                OutFrames                     .ForwardOutbound
                InDiscards                    .DiscardInbound
            dot1dStatic
              StaticTable
                Address
                ReceivePort
                AllowedToGoTo
                Status

   The following IEEE 802.1d management objects have not been included
   in the Bridge MIB for the indicated reasons.

          IEEE 802.1d Object              Disposition

          Bridge.BridgeName               Same as sysDescr (MIB II)
          Bridge.BridgeUpTime             Same as sysUpTime (MIB II)
          Bridge.PortAddresses            Same as ifPhysAddress (MIB II)
          BridgePort.PortName             Same as ifDescr (MIB II)
          BridgePort.PortType             Same as ifType (MIB II)
          BridgePort.RoutingType          Derivable from the implemented
                                          groups

          SpanningTreeProtocol
              .BridgeIdentifier           Combination of dot1dStpPriority
                                          and dot1dBaseBridgeAddress
              .TopologyChange             Since this is transitory, it
                                          is not considered useful.
          SpanningTreeProtocolPort
              .Uptime                     Same as ifLastChange (MIB II)
              .PortIdentifier             Combination of dot1dStpPort
                                          and dot1dStpPortPriority
              .TopologyChangeAcknowledged Since this is transitory, it
                                          is not considered useful.
              .DiscardLackOfBuffers       Redundant

          Transmission Priority           These objects are not required
                                          as per the Pics Proforma and
                                          not considered useful.
              .TransmissionPriorityName
              .OutboundUserPriority
              .OutboundAccessPriority





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3.1.1.  The dot1dBase Group

   This mandatory group contains the objects which are applicable to all
   types of bridges.

3.1.2.  The dot1dStp Group

   This group contains the objects that denote the bridge's state with
   respect to the Spanning Tree Protocol.  If a node does not
   implemented the Spanning Tree Protocol, this group will not be
   implemented.

3.1.3.  The dot1dSr Group

   This group contains the objects that describe the entity's state with
   respect to source route bridging.  If source routing is not supported
   this group will not be implemented.  This group is applicable to
   source route only, and SRT bridges.  This group will be described in
   a separate document applicable only to source route bridging.

3.1.4.  The dot1dTp Group

   This group contains objects that describe the entity's state with
   respect to transparent bridging.  If transparent bridging is not
   supported this group will not be implemented.  This group is
   applicable to transparent only and SRT bridges.

3.1.5.  The dot1dStatic Group

   This group contains objects that describe the entity's state with
   respect to destination-address filtering.  If destination-address
   filtering is not supported this group will not be implemented.  This
   group is applicable to any type of bridge which performs
   destination-address filtering.

3.2.  Relationship to Other MIBs

   As described above, some IEEE 802.1d management objects have not been
   included in this MIB because they overlap with objects in other MIBs
   applicable to a bridge implementing this MIB.  In particular, it is
   assumed that a bridge implementing this MIB will also implement (at
   least) the 'system' group and the 'interfaces' group defined in MIB-
   II [6].