rfc1286.txt

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Network Working Group                                          E. Decker
Request for Comments: 1286                           cisco Systems, Inc.
                                                             P. Langille
                                           Digital Equipment Corporation
                                                          A. Rijsinghani
                                           Digital Equipment Corporation
                                                           K. McCloghrie
                                                Hughes LAN Systems, Inc.
                                                           December 1991


               Definitions of Managed Objects for Bridges

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 Structure of MIB ....................................    4
   4.1.1 The dot1dBase Group ...............................    7
   4.1.2 The dot1dStp Group ................................    7
   4.1.3 The dot1dSr Group .................................    7
   4.1.4 The dot1dTp Group .................................    7
   4.1.5 The dot1dStatic Group .............................    7
   4.2 Relationship to Other MIBs ..........................    7
   4.2.1 Relationship to the 'system' group ................    8
   4.2.2 Relationship to the 'interfaces' group ............    8
   4.3 Textual Conventions .................................    9
   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 dot1dSr Group Definitions .......................   22
   5.5 The dot1dTp Group Definitions .......................   28
   5.6 The dot1dStatic Group Definitions ...................   34
   5.8 Traps for use by Bridges ............................   36
   6. Acknowledgments ......................................   37



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   7. References ...........................................   38
   8. Security Considerations...............................   39
   9. Authors' Addresses....................................   40

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

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.




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   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 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 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].

4.  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].  Source route
   bridging has been defined by I.B.M. and is described in the Token
   Ring Architecture Reference [12].  IEEE 802.1d is currently working
   on combining the source route and transparent techniques in a
   compatible fashion.  This memo defines those objects needed for the
   management of a bridging entity operating in one of these modes.

   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.




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      (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.

4.1.  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.

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



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      State                         .SpanningTreeState
      Enable
      PathCost                      .PortPathCost
      DesignatedRoot                .DesignatedRoot
      DesignatedCost                .DesignatedCost
      DesignatedBridge              .DesignatedBridge
      DesignatedPort                .DesignatedPort
      ForwardTransitions

  dot1dSr
    PortTable
      Port
      HopCount                    SourceRoutingPort
                                    .PortHopCount
      LocalSegment                  .SegmentNumber
      BridgeNum                     .BridgeNumber
      TargetSegment
      LargestFrame                  .LargestFrameSize
      STESpanMode                   .LimitedBroadcastMode
      SpecInFrames                BridgePort
                                    .ValidSRFramesReceived
      SpecOutFrames                 .ValidSRForwardedOutbound
      ApeInFrames
      ApeOutFrames                  .BroadcastFramesForwarded
      SteInFrames
      SteOutFrames                  .BroadcastFramesForwarded
      SegmentMismatchDiscards       .DiscardInvalidRI
      DuplicateSegmentDiscards      .LanIdMismatch
      HopCountExceededDiscards      .FramesDiscardedHopCountExceeded
  dot1dTp
    LearnedEntryDiscards          BridgeFilter.DatabaseSize
                                    .NumDynamic,NumStatic
    AgingTime                     BridgeFilter.AgingTime
    FdbTable
      Address
      Status
      Port
    PortTable
      Port
      MaxInfo
      InFrames                    BridgePort.FramesReceived
      OutFrames                     .ForwardOutbound
      InDiscards                    .DiscardInbound
  dot1dStatic
    StaticTable
      Address
      ReceivePort
      AllowedToGoTo



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      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 dot1dStpPortNum
                                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

SourceRoutingPort               The Source Routing Supplement,
                                at the time of this writing,
                                is not stable. The following
                                objects were NOT included in
                                this MIB because they are
                                redundant or not considered
                                useful.
    .LimitedBroadcastEnable
BridgePort.DupLanIdOrTreeError
    .DiscardLackOfBuffers
    .DiscardErrorDetails
    .DiscardTargetLANInoperable



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    .ValidSRDiscardedInbound
    .BroadcastBytesForwarded
    .NonBroadcastBytesForwarded
    .FramesNotReceivedDueToCongestion
    .FramesDiscardedDueToInternalError

4.1.1.  The dot1dBase Group

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

4.1.2.  The dot1dStp Group

   This group contains the objects that denote the bridge's state with