





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
   respect to the Spanning Tree Protocol.  If a node does not
   implemented the Spanning Tree Protocol, this group will not be
   implemented.  This group is applicable to any transparent only,
   source route, or SRT bridge which implements the Spanning Tree
   Protocol.

4.1.3.  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.

4.1.4.  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.

4.1.5.  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.

4.2.  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



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   least) the 'system' group and the 'interfaces' group defined in MIB-
   II [6].

4.2.1.  Relationship to the 'system' group

   In MIB-II, the 'system' group is defined as being mandatory for all
   systems such that each managed entity contains one instance of each
   object in the 'system' group.  Thus, those objects apply to the
   entity as a whole irrespective of whether the entity's sole
   functionality is bridging, or whether bridging is only a subset of
   the entity's functionality.

4.2.2.  Relationship to the 'interfaces' group

   In MIB-II, the 'interfaces' group is defined as being mandatory for
   all systems and contains information on an entity's interfaces, where
   each interface is thought of as being attached to a `subnetwork'.
   (Note that this term is not to be confused with `subnet' which refers
   to an addressing partitioning scheme used in the Internet suite of
   protocols.) The term 'segment' is used in this memo to refer to such
   a subnetwork, whether it be an Ethernet segment, a 'ring', a WAN
   link, or even an X.25 virtual circuit.

   Implicit in this Bridge MIB is the notion of ports on a bridge.  Each
   of these ports is associated with one interface of the 'interfaces'
   group, and in most situations, each port is associated with a
   different interface. However, there are situations in which multiple
   ports are associated with the same interface.  An example of such a
   situation would be several ports each corresponding one-to-one with
   several X.25 virtual circuits but all on the same interface.

   Each port is uniquely identified by a port number.  A port number has
   no mandatory relationship to an interface number, but in the simple
   case a port number will have the same value as the corresponding
   interface's interface number.  Port numbers are in the range
   (1..dot1dBaseNumPorts).

   Some entities perform other functionality as well as bridging through
   the sending and receiving of data on their interfaces.  In such
   situations, only a subset of the data sent/received on an interface
   is within the domain of the entity's bridging functionality.  This
   subset is considered to be delineated according to a set of
   protocols, with some protocols being bridged, and other protocols not
   being bridged. For example, in an entity which exclusively performed
   bridging, all protocols would be considered as being bridged, whereas
   in an entity which performed IP routing on IP datagrams and only
   bridged other protocols, only the non-IP data would be considered as
   being bridged.



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   Thus, this Bridge MIB (and in particular, its counters) are
   applicable only to that subset of the data on an entity's interfaces
   which is sent/received for a protocol being bridged.  All such data
   is sent/received via the ports of the bridge.

4.3.  Textual Conventions

   The datatypes, MacAddress, BridgeId and Timeout, are used as textual
   conventions in this document.  These textual conventions have NO
   effect on either the syntax nor the semantics of any managed object.
   Objects defined using these conventions are always encoded by means
   of the rules that define their 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.

5.  Definitions

   RFC1286-MIB DEFINITIONS ::= BEGIN

   IMPORTS
           Counter, Gauge, TimeTicks
                   FROM RFC1155-SMI
           mib-2
                   FROM RFC1213-MIB
           OBJECT-TYPE
                   FROM RFC-1212
           TRAP-TYPE
                   FROM RFC-1215;

   -- All representations of MAC addresses in this MIB Module use,
   -- as a textual convention (i.e. this convention does not affect
   -- their encoding), the data type:

   MacAddress ::= OCTET STRING (SIZE (6))    -- a 6 octet address in
                                             -- the "canonical" order
   -- defined by IEEE 802.1a, i.e., as if it were transmitted least
   -- significant bit first, even though 802.5 (in contrast to other
   -- 802.x protocols) requires MAC addresses to be transmitted most
   -- significant bit first.
   --
   -- 16-bit addresses, if needed, are represented by setting their
   -- upper 4 octets to all 0's, i.e., AAFF would be represented
   -- as 00000000AAFF.


   -- Similarly, all representations of Bridge-Id in this MIB Module
   -- use, as a textual convention (i.e. this convention does not affect
   -- their encoding), the data type:



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   BridgeId ::= OCTET STRING (SIZE (8))   -- the Bridge-Identifier as
                                          -- used in the Spanning Tree
   -- Protocol to uniquely identify a bridge.  Its first two octets
   -- (in network byte order) contain a priority value and its last
   -- 6 octets contain the MAC address used to refer to a bridge in a
   -- unique fashion (typically, the numerically smallest MAC address
   -- of all ports on the bridge).
   -- Several objects in this MIB module represent values of timers
   -- used by the Spanning Tree Protocol.  In this MIB, these timers
   -- have values in units of hundreths of a second (i.e. 1/100 secs).
   -- These timers, when stored in a Spanning Tree Protocol's BPDU,
   -- are in units of 1/256 seconds.  Note, however, that 802.1d/D9
   -- specifies a settable granularity of no more than 1 second for
   -- these timers.  To avoid ambiguity, a data type is defined here
   -- as a textual convention and all representation of these timers
   -- in this MIB module are defined using this data type.  An algorithm
   -- is also defined for converting between the different units, to
   -- ensure a timer's value is not distorted by multiple conversions.
   -- The data type is:

   Timeout ::= INTEGER      -- a STP timer in units of 1/100 seconds

   -- To convert a Timeout value into a value in units of
   -- 1/256 seconds, the following algorithm should be used:
   --
   --      b  = floor( (n * 256) / 100)
   --
   -- where:
   --      floor   =  quotient [ignore remainder]
   --      n is the value in 1/100 second units
   --      b is the value in 1/256 second units
   --
   -- To convert the value from 1/256 second units back to
   -- 1/100 seconds, the following algorithm should be used:
   --
   --      n = ceiling( (b * 100) / 256)
   --
   -- where:
   --      ceiling =  quotient [if remainder is 0], or
   --                 quotient + 1 [if remainder is non-zero]
   --      n is the value in 1/100 second units
   --      b is the value in 1/256 second units
   --
   -- Note: it is important that the arithmetic operations are done
   -- in the order specified (i.e., multiply first, divide second).

   dot1dBridge   OBJECT IDENTIFIER ::= { mib-2 17 }




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   -- groups in the Bridge MIB

   dot1dBase     OBJECT IDENTIFIER ::= { dot1dBridge 1 }

   dot1dStp      OBJECT IDENTIFIER ::= { dot1dBridge 2 }

   dot1dSr       OBJECT IDENTIFIER ::= { dot1dBridge 3 }

   dot1dTp       OBJECT IDENTIFIER ::= { dot1dBridge 4 }

   dot1dStatic   OBJECT IDENTIFIER ::= { dot1dBridge 5 }


   -- the dot1dBase group

   -- Implementation of the dot1dBase group is mandatory for all
   -- bridges.

   dot1dBaseBridgeAddress OBJECT-TYPE
       SYNTAX  MacAddress
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The MAC address used by this bridge when it must
               be referred to in a unique fashion.   It is
               recommended that this be the numerically smallest
               MAC address of all ports that belong to this
               bridge.  However it is only required to be unique.
               When concatenated with dot1dStpPriority a unique
               BridgeIdentifier is formed which is used in the
               Spanning Tree Protocol."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Sections 6.4.1.1.3 and 3.12.5"
       ::= { dot1dBase 1 }

   dot1dBaseNumPorts OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of ports controlled by this bridging
               entity."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.4.1.1.3"
       ::= { dot1dBase 2 }

   dot1dBaseType OBJECT-TYPE
       SYNTAX  INTEGER {



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                   unknown(1),
                   transparent-only(2),
                   sourceroute-only(3),
                   srt(4)
               }
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "Indicates what type of bridging this bridge can
               perform.  If a bridge is actually performing a
               certain type of bridging this will be indicated by
               entries in the port table for the given type."
       ::= { dot1dBase 3 }

   -- The Generic Bridge Port Table

   dot1dBasePortTable OBJECT-TYPE
       SYNTAX  SEQUENCE OF Dot1dBasePortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A table that contains generic information about
               every port that is associated with this bridge.
               Transparent, source-route, and srt ports are
               included."
       ::= { dot1dBase 4 }

   dot1dBasePortEntry OBJECT-TYPE
       SYNTAX  Dot1dBasePortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A list of information for each port of the
               bridge."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.4.2, 6.6.1"
       INDEX  { dot1dBasePort }
       ::= { dot1dBasePortTable 1 }

   Dot1dBasePortEntry ::=
       SEQUENCE {
           dot1dBasePort
               INTEGER,
           dot1dBasePortIfIndex
               INTEGER,
           dot1dBasePortCircuit
               OBJECT IDENTIFIER,
           dot1dBasePortDelayExceededDiscards



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               Counter,
           dot1dBasePortMtuExceededDiscards
               Counter
       }

   dot1dBasePort OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The port number of the port for which this entry
               contains bridge management information."
       ::= { dot1dBasePortEntry 1 }

   dot1dBasePortIfIndex OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The value of the instance of the ifIndex object,
               defined in [4,6], for the interface corresponding
               to this port."
       ::= { dot1dBasePortEntry 2 }

   dot1dBasePortCircuit OBJECT-TYPE
       SYNTAX  OBJECT IDENTIFIER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "For a port which (potentially) has the same value
               of dot1dBasePortIfIndex as another port on the
               same bridge, this object contains the name of an
               object instance unique to this port.  For example,
               in the case where multiple ports correspond one-
               to-one with multiple X.25 virtual circuits, this
               value might identify an (e.g., the first) object
               instance associated with the X.25 virtual circuit
               corresponding to this port.

               For a port which has a unique value of
               dot1dBasePortIfIndex, this object can have the
               value { 0 0 }."
       ::= { dot1dBasePortEntry 3 }

   dot1dBasePortDelayExceededDiscards OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory



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       DESCRIPTION
               "The number of frames discarded by this port due
               to excessive transit delay through the bridge.  It
               is incremented by both transparent and source
               route bridges."
       REFERENCE
                "P802.1d/D9, July 14, 1989: Section 6.6.1.1.3"
       ::= { dot1dBasePortEntry 4 }

   dot1dBasePortMtuExceededDiscards OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of frames discarded by this port due
               to an excessive size.  It is incremented by both
               transparent and source route bridges."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.6.1.1.3"
       ::= { dot1dBasePortEntry 5 }


   -- the dot1dStp group

   -- Implementation of the dot1dStp group is optional.  It is
   -- implemented by those bridges that support the Spanning Tree
   -- Protocol.  Transparent, Source Route, and SRT bridges will
   -- implement this group only if they support the Spanning Tree
   -- Protocol.


   dot1dStpProtocolSpecification OBJECT-TYPE
       SYNTAX  INTEGER {
                   unknown(1),
                   decLb100(2),
                   ieee8021d(3)
               }
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "An indication of what version of the Spanning
               Tree Protocol is being run.  The value
               'decLb100(2)' indicates the DEC LANbridge 100
               Spanning Tree protocol.  IEEE 802.1d
               implementations will return 'ieee8021d(3)'.  If
               future versions of the IEEE Spanning Tree Protocol
               are released that are incompatible with the
               current version a new value will be defined."



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       ::= { dot1dStp 1 }

   dot1dStpPriority OBJECT-TYPE
       SYNTAX  INTEGER (0..65535)
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The value of the write-able portion of the Bridge
               ID, i.e., the first two octets of the (8 octet
               long) Bridge ID.  The other (last) 6 octets of the
               Bridge ID are given by the value of
               dot1dBaseBridgeAddress."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.7"
       ::= { dot1dStp 2 }

   dot1dStpTimeSinceTopologyChange OBJECT-TYPE
       SYNTAX  TimeTicks
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The time (in hundredths of a second) since the
               last time a topology change was detected by the
               bridge entity."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.8.1.1.3"
       ::= { dot1dStp 3 }

   dot1dStpTopChanges OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The total number of topology changes detected by
               this bridge since the management entity was last
               reset or initialized."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.8.1.1.3"
       ::= { dot1dStp 4 }

   dot1dStpDesignatedRoot OBJECT-TYPE
       SYNTAX  BridgeId
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The bridge identifier of the root of the spanning
               tree as determined by the Spanning Tree Protocol
               as executed by this node.  This value is used as



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               the Root Identifier parameter in all Configuration
               Bridge PDUs originated by this node."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.1"
       ::= { dot1dStp 5 }

   dot1dStpRootCost OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The cost of the path to the root as seen from
               this bridge."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.2"
       ::= { dot1dStp 6 }

   dot1dStpRootPort OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The port number of the port which offers the
               lowest cost path from this bridge to the root
               bridge."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.3"
       ::= { dot1dStp 7 }

   dot1dStpMaxAge OBJECT-TYPE
       SYNTAX  Timeout
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The maximum age of Spanning Tree Protocol
               information learned from the network on any port
               before it is discarded, in units of hundredths of
               a second.  This is the actual value that this
               bridge is currently using."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.4"
       ::= { dot1dStp 8 }

   dot1dStpHelloTime OBJECT-TYPE
       SYNTAX  Timeout
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION



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               "The amount of time between the transmission of
               Configuration bridge PDUs by this node on any port
               when it is the root of the spanning tree or trying
               to become so, in units of hundredths of a second.
               This is the actual value that this bridge is
               currently using."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.5"
       ::= { dot1dStp 9 }

   dot1dStpHoldTime OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "This time value determines the interval length
               during which no more than two Configuration bridge
               PDUs shall be transmitted by this node, in units
               of hundredths of a second."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.14"
       ::= { dot1dStp 10 }

   dot1dStpForwardDelay OBJECT-TYPE
       SYNTAX  Timeout
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "This time value, measured in units of hundredths
               of a second, controls how fast a port changes its
               spanning state when moving towards the Forwarding
               state.  The value determines how long the port
               stays in a particular state before moving to the
               next state.  For example, how long a port stays in
               the Listening state when moving from Blocking to
               Learning.  This value is also used, when a
               topology change has been detected and is underway,
               to age all dynamic entries in the Forwarding
               Database.  [Note that this value is the one that
               this bridge is currently using, in contrast to
               dot1dStpBridgeForwardDelay which is the value that
               this bridge and all others would start using
               if/when this bridge were to become the root.]"
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.6"
       ::= { dot1dStp 11 }





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   dot1dStpBridgeMaxAge OBJECT-TYPE
       SYNTAX  Timeout (600..4000)
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The value that all bridges use for MaxAge when
               this bridge is acting as the root.  Note that
               802.1d/D9 specifies that the range for this
               parameter is related to the value of
               dot1dStpBridgeHelloTime. The granularity of this
               timer is specified by 802.1d/D9 to be 1 second.
               An agent may return a badValue error if a set is
               attempted to a value which is not a whole number
               of seconds."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.8"
       ::= { dot1dStp 12 }

   dot1dStpBridgeHelloTime OBJECT-TYPE
       SYNTAX  Timeout (100..1000)
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The value that all bridges use for HelloTime when
               this bridge is acting as the root.  The
               granularity of this timer is specified by
               802.1d/D9 to be 1 second.  An agent may return a
               badValue error if a set is attempted to a value
               which is not a whole number of seconds."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.3.9"
       ::= { dot1dStp 13 }

   dot1dStpBridgeForwardDelay OBJECT-TYPE
       SYNTAX  Timeout (400..3000)
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The value that all bridges use for ForwardDelay
               when this bridge is acting as the root.  Note that
               802.1d/D9 specifies that the range for this
               parameter is related to the value of
               dot1dStpBridgeMaxAge.  The granularity of this
               timer is specified by 802.1d/D9 to be 1 second.
               An agent may return a badValue error if a set is
               attempted to a value which is not a whole number
               of seconds."
       REFERENCE



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               "P802.1d/D9, July 14, 1989: Section 4.5.3.10"
       ::= { dot1dStp 14 }


   -- The Spanning Tree Port Table

   dot1dStpPortTable OBJECT-TYPE
       SYNTAX  SEQUENCE OF Dot1dStpPortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A table that contains port-specific information
               for the Spanning Tree Protocol."
       ::= { dot1dStp 15 }

   dot1dStpPortEntry OBJECT-TYPE
       SYNTAX  Dot1dStpPortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A list of information maintained by every port
               about the Spanning Tree Protocol state for that
               port."
       INDEX   { dot1dStpPort }
       ::= { dot1dStpPortTable 1 }

   Dot1dStpPortEntry ::=
       SEQUENCE {
           dot1dStpPort
               INTEGER,
           dot1dStpPortPriority
               INTEGER,
           dot1dStpPortState
               INTEGER,
           dot1dStpPortEnable
               INTEGER,
           dot1dStpPortPathCost
               INTEGER,
           dot1dStpPortDesignatedRoot
               BridgeId,
           dot1dStpPortDesignatedCost
               INTEGER,
           dot1dStpPortDesignatedBridge
               BridgeId,
           dot1dStpPortDesignatedPort
               OCTET STRING,
           dot1dStpPortForwardTransitions
               Counter



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       }

   dot1dStpPort OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The port number of the port for which this entry
               contains Spanning Tree Protocol management
               information."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.8.2.1.2"
       ::= { dot1dStpPortEntry 1 }

   dot1dStpPortPriority OBJECT-TYPE
       SYNTAX  INTEGER (0..255)
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The value of the priority field which is
               contained in the first (in network byte order)
               octet of the (2 octet long) Port ID.  The other
               octet of the Port ID is given by the value of
               dot1dStpPort."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.1"
       ::= { dot1dStpPortEntry 2 }

   dot1dStpPortState OBJECT-TYPE
       SYNTAX  INTEGER {
                   disabled(1),
                   blocking(2),
                   listening(3),
                   learning(4),
                   forwarding(5),
                   broken(6)
               }
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The port's current state as defined by
               application of the Spanning Tree Protocol.  This
               state controls what action a port takes on
               reception of a frame.  If the bridge has detected
               a port that is malfunctioning it will place that
               port into the broken(6) state.  For ports which
               are disabled (see dot1dStpPortEnable), this object
               will have a value of disabled(1)."



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       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.2"
       ::= { dot1dStpPortEntry 3 }

   dot1dStpPortEnable OBJECT-TYPE
       SYNTAX  INTEGER {
                   enabled(1),
                   disabled(2)
               }
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The enabled/disabled status of the port."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.2"
       ::= { dot1dStpPortEntry 4 }

   dot1dStpPortPathCost OBJECT-TYPE
       SYNTAX  INTEGER (1..65535)
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The contribution of this port to the path cost of
               paths towards the spanning tree root which include
               this port."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.3"
       ::= { dot1dStpPortEntry 5 }

   dot1dStpPortDesignatedRoot OBJECT-TYPE
       SYNTAX  BridgeId
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The unique Bridge Identifier of the Bridge
               recorded as the Root in the Configuration BPDUs
               transmitted by the Designated Bridge for the
               segment to which the port is attached."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.4"
       ::= { dot1dStpPortEntry 6 }

   dot1dStpPortDesignatedCost OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The path cost of the Designated Port of the



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               segment connected to this port.  This value is
               compared to the Root Path Cost field in received
               bridge PDUs."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.5"
       ::= { dot1dStpPortEntry 7 }

   dot1dStpPortDesignatedBridge OBJECT-TYPE
       SYNTAX  BridgeId
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The Bridge Identifier of the bridge which this
               port considers to be the Designated Bridge for
               this port's segment."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.6"
       ::= { dot1dStpPortEntry 8 }

   dot1dStpPortDesignatedPort OBJECT-TYPE
       SYNTAX  OCTET STRING (SIZE (2))
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The Port Identifier of the port on the Designated
               Bridge for this port's segment."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 4.5.5.7"
       ::= { dot1dStpPortEntry 9 }

   dot1dStpPortForwardTransitions OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of times this port has transitioned
               from the Learning state to the Forwarding state."
       ::= { dot1dStpPortEntry 10 }


   -- the dot1dSr group

   -- Implementation of the dot1dSr group is optional.  It is
   -- implemented by those bridges that support the source route
   -- bridging mode, including Source Route and SRT bridges.






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   dot1dSrPortTable OBJECT-TYPE
       SYNTAX  SEQUENCE OF Dot1dSrPortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A table that contains information about every
               port that is associated with this source route
               bridge."
       ::= { dot1dSr 1 }

   dot1dSrPortEntry OBJECT-TYPE
       SYNTAX  Dot1dSrPortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A list of information for each port of a source
               route bridge."
       INDEX   { dot1dSrPort }
       ::= { dot1dSrPortTable 1 }

   Dot1dSrPortEntry ::=
       SEQUENCE {
           dot1dSrPort
               INTEGER,
           dot1dSrPortHopCount
               INTEGER,
           dot1dSrPortLocalSegment
               INTEGER,
           dot1dSrPortBridgeNum
               INTEGER,
           dot1dSrPortTargetSegment
               INTEGER,
           dot1dSrPortLargestFrame
               INTEGER,
           dot1dSrPortSTESpanMode
               INTEGER,
           dot1dSrPortSpecInFrames
               Counter,
           dot1dSrPortSpecOutFrames
               Counter,
           dot1dSrPortApeInFrames
               Counter,
           dot1dSrPortApeOutFrames
               Counter,
           dot1dSrPortSteInFrames
               Counter,
           dot1dSrPortSteOutFrames
               Counter,



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           dot1dSrPortSegmentMismatchDiscards
               Counter,
           dot1dSrPortDuplicateSegmentDiscards
               Counter,
           dot1dSrPortHopCountExceededDiscards
               Counter
       }

   dot1dSrPort OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The port number of the port for which this entry
               contains Source Route management information."
       ::= { dot1dSrPortEntry 1 }

   dot1dSrPortHopCount OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The maximum number of routing descriptors allowed
               in an All Paths or Spanning Tree Explorer frames."
       ::= { dot1dSrPortEntry 2 }

   dot1dSrPortLocalSegment OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The segment number that uniquely identifies the
               segment to which this port is connected. Current
               source routing protocols limit this value to the
               range: 0 through 4095. A value of 65535 signifies
               that no segment number is assigned to this port."
       ::= { dot1dSrPortEntry 3 }

   dot1dSrPortBridgeNum OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "A bridge number uniquely identifies a bridge when
               more than one bridge is used to span the same two
               segments.  Current source routing protocols limit
               this value to the range: 0 through 15. A value of
               65535 signifies that no bridge number is assigned



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               to this bridge."
       ::= { dot1dSrPortEntry 4 }

   dot1dSrPortTargetSegment OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The segment number that corresponds to the target
               segment this port is considered to be connected to
               by the bridge.  Current source routing protocols
               limit this value to the range: 0 through 4095. A
               value of 65535 signifies that no target segment is
               assigned to this port."
       ::= { dot1dSrPortEntry 5 }

   -- It would be nice if we could use ifMtu as the size of the
   -- largest frame, but we can't because ifMtu is defined to be
   -- the size that the (inter-)network layer can use which can
   -- differ from the MAC layer (especially if several layers of
   -- encapsulation are used).

   dot1dSrPortLargestFrame OBJECT-TYPE
       SYNTAX  INTEGER {
                   dot1dSrMtu516   (516),
                   dot1dSrMtu1500  (1500),
                   dot1dSrMtu2052  (2052),
                   dot1dSrMtu4472  (4472),
                   dot1dSrMtu8144  (8144),
                   dot1dSrMtu11407 (11407), -- yes this is correct don't
                   dot1dSrMtu17800 (17800), -- ask me where it came from.
                   dot1dSrMtu65535 (65535)
               }

       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The maximum size of the INFO field (LLC and
               above) that this port can send/receive.  It does
               not include any MAC level (framing) octets.  The
               value of this object is used by this bridge to
               determine whether a modification of the
               LargestFrame (LF, see [14]) field of the Routing
               Control field of the Routing Information Field is
               necessary.  Valid values as defined by the 802.5
               source routing bridging specification[14] are 516,
               1500, 2052, 4472, 8144, 11407, 17800, and 65535
               octets.  Behavior of the port when an illegal



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               value is written is implementation specific.  It
               is recommended that a reasonable legal value be
               chosen."
       ::= { dot1dSrPortEntry 6 }

   dot1dSrPortSTESpanMode OBJECT-TYPE
       SYNTAX  INTEGER {
                   auto-span(1),
                   disabled(2),
                   forced(3)
               }
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "Determines how this port behaves when presented
               with a Spanning Tree Explorer frame.  The value
               'disabled(2)' indicates that the port will not
               accept or send Spanning Tree Explorer packets; any
               STE packets received will be silently discarded.
               The value 'forced(3)' indicates the port will
               always accept and propagate Spanning Tree Explorer
               frames.  This allows a manually configured
               Spanning Tree for this class of packet to be
               configured.  Note that unlike transparent bridging
               this is not catastrophic to the network if there
               are loops.  The value 'auto-span(1)' can only be
               returned by a bridge that both implements the
               Spanning Tree Protocol and has use of the protocol
               enabled on this port. The behavior of the port for
               Spanning Tree Explorer frames is determined by the
               state of dot1dStpPortState.  If the port is in the
               'forwarding' state, the frame will be accepted or
               propagated.  Otherwise it will be silently
               discarded."
       ::= { dot1dSrPortEntry 7 }

   dot1dSrPortSpecInFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of specifically routed frames that
               have been received from this port's segment."
       ::= { dot1dSrPortEntry 8 }

   dot1dSrPortSpecOutFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only



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       STATUS  mandatory
       DESCRIPTION
               "The number of specifically routed frames that
               this port has transmitted on its segment."
       ::= { dot1dSrPortEntry 9 }

   dot1dSrPortApeInFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of all paths explorer frames that have
               been received by this port from its segment."
       ::= { dot1dSrPortEntry 10 }

   dot1dSrPortApeOutFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of all paths explorer frames that have
               been transmitted by this port on its segment."
       ::= { dot1dSrPortEntry 11 }

   dot1dSrPortSteInFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of spanning tree explorer frames that
               have been received by this port from its segment."
       ::= { dot1dSrPortEntry 12 }

   dot1dSrPortSteOutFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of spanning tree explorer frames that
               have been transmitted by this port on its
               segment."
       ::= { dot1dSrPortEntry 13 }

   dot1dSrPortSegmentMismatchDiscards OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION



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               "The number of explorer frames that have been
               discarded by this port because the routing
               descriptor field contained an invalid adjacent
               segment value."
       ::= { dot1dSrPortEntry 14 }

   dot1dSrPortDuplicateSegmentDiscards OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of frames that have been discarded by
               this port because the routing descriptor field
               contained a duplicate segment identifier."
       ::= { dot1dSrPortEntry 15 }

   dot1dSrPortHopCountExceededDiscards OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of explorer frames that have been
               discarded by this port because the Routing
               Information Field has exceeded the maximum route
               descriptor length."
       ::= { dot1dSrPortEntry 16 }


   -- the dot1dTp group

   -- Implementation of the dot1dTp group is optional.  It is
   -- implemented by those bridges that support the transparent
   -- bridging mode.  A transparent or SRT bridge will implement
   -- this group.


   dot1dTpLearnedEntryDiscards OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The total number of Forwarding Database entries,
               which have been or would have been learnt, but
               have been discarded due to a lack of space to
               store them in the Forwarding Database.  If this
               counter is increasing, it indicates that the
               Forwarding Database is regularly becoming full (a
               condition which has unpleasant performance effects



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               on the subnetwork).  If this counter has a
               significant value but is not presently increasing,
               it indicates that the problem has been occurring
               but is not persistent."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.7.1.1.3"
       ::= { dot1dTp 1 }

   dot1dTpAgingTime OBJECT-TYPE
       SYNTAX   INTEGER
       ACCESS   read-write
       STATUS   mandatory
       DESCRIPTION
               "The timeout period in seconds for aging out
               dynamically learned forwarding information."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.7.1.1.3"
       ::= { dot1dTp 2 }


   --  The Forwarding Database for Transparent Bridges

   dot1dTpFdbTable OBJECT-TYPE
       SYNTAX  SEQUENCE OF Dot1dTpFdbEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A table that contains information about unicast
               entries for which the bridge has forwarding and/or
               filtering information.  This information is used
               by the transparent bridging function in
               determining how to propagate a received frame."
       ::= { dot1dTp 3 }

   dot1dTpFdbEntry OBJECT-TYPE
       SYNTAX  Dot1dTpFdbEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "Information about a specific unicast MAC address
               for which the bridge has some forwarding and/or
               filtering information."
       INDEX   { dot1dTpFdbAddress }
       ::= { dot1dTpFdbTable 1 }

   Dot1dTpFdbEntry ::=
       SEQUENCE {
           dot1dTpFdbAddress



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               MacAddress,
           dot1dTpFdbPort
               INTEGER,
           dot1dTpFdbStatus
               INTEGER
       }

   dot1dTpFdbAddress OBJECT-TYPE
       SYNTAX  MacAddress
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "A unicast MAC address for which the bridge has
               forwarding and/or filtering information."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 3.9.1, 3.9.2"
       ::= { dot1dTpFdbEntry 1 }

   dot1dTpFdbPort OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "Either the value '0', or the port number of the
               port on which a frame having a source address
               equal to the value of the corresponding instance
               of dot1dTpFdbAddress has been seen.  A value of
               '0' indicates that the port number has not been
               learned but that the bridge does have some
               forwarding/filtering information about this
               address (e.g. in the dot1dStaticTable).
               Implementors are encouraged to assign the port
               value to this object whenever it is learned even
               for addresses for which the corresponding value of
               dot1dTpFdbStatus is not learned(3)."

       ::= { dot1dTpFdbEntry 2 }

   dot1dTpFdbStatus OBJECT-TYPE
       SYNTAX  INTEGER {
                   other(1),
                   invalid(2),
                   learned(3),
                   self(4),
                   mgmt(5)
               }
       ACCESS  read-only
       STATUS  mandatory



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       DESCRIPTION
               "The status of this entry.  The meanings of the
               values are:

                 other(1)   : none of the following.  This would
                              include the case where some other
                              MIB object (not the corresponding
                              instance of dot1dTpFdbPort, nor an
                              entry in the dot1dStaticTable) is
                              being used to determine if and how
                              frames addressed to the value of
                              the corresponding instance of
                              dot1dTpFdbAddress are being
                              forwarded.

                 invalid(2) : this entry is not longer valid
                              (e.g., it was learned but has since
                              aged-out), but has not yet been
                              flushed from the table.

                 learned(3) : the value of the corresponding
                              instance of dot1dTpFdbPort was
                              learned, and is being used.

                 self(4)    : the value of the corresponding
                              instance of dot1dTpFdbAddress
                              represents one of the bridge's
                              addresses.  The corresponding
                              instance of dot1dTpFdbPort
                              indicates which of the bridge's
                              ports has this address.

                 mgmt(5)    : the value of the corresponding
                              instance of dot1dTpFdbAddress is
                              also the value of an existing
                              instance of dot1dStaticAddress."
       ::= { dot1dTpFdbEntry 3 }


   --  Port Table for Transparent Bridges

   dot1dTpPortTable OBJECT-TYPE
       SYNTAX  SEQUENCE OF Dot1dTpPortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A table that contains information about every
               port that is associated with this transparent



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               bridge."
       ::= { dot1dTp 4 }

   dot1dTpPortEntry OBJECT-TYPE
       SYNTAX  Dot1dTpPortEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A list of information for each port of a
               transparent bridge."
       INDEX   { dot1dTpPort }
       ::= { dot1dTpPortTable 1 }

   Dot1dTpPortEntry ::=
       SEQUENCE {
           dot1dTpPort
               INTEGER,
           dot1dTpPortMaxInfo
               INTEGER,
           dot1dTpPortInFrames
               Counter,
           dot1dTpPortOutFrames
               Counter,
           dot1dTpPortInDiscards
               Counter
       }

   dot1dTpPort OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The port number of the port for which this entry
               contains Transparent bridging management
               information."
       ::= { dot1dTpPortEntry 1 }

   -- It would be nice if we could use ifMtu as the size of the
   -- largest INFO field, but we can't because ifMtu is defined
   -- to be the size that the (inter-)network layer can use which
   -- can differ from the MAC layer (especially if several layers
   -- of encapsulation are used).

   dot1dTpPortMaxInfo OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION



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               "The maximum size of the INFO (non-MAC) field that
               this port will receive or transmit."
       ::= { dot1dTpPortEntry 2 }

   dot1dTpPortInFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of frames that have been received by
               this port from its segment. Note that a frame
               received on the interface corresponding to this
               port is only counted by this object if and only if
               it is for a protocol being processed by the local
               bridging function."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.6.1.1.3"
       ::= { dot1dTpPortEntry 3 }

   dot1dTpPortOutFrames OBJECT-TYPE
       SYNTAX  Counter
       ACCESS  read-only
       STATUS  mandatory
       DESCRIPTION
               "The number of frames that have been transmitted
               by this port to its segment.  Note that a frame
               transmitted on the interface corresponding to this
               port is only counted by this object if and only if
               it is for a protocol being processed by the local
               bridging function."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.6.1.1.3"
       ::= { dot1dTpPortEntry 4 }

   dot1dTpPortInDiscards OBJECT-TYPE
       SYNTAX   Counter
       ACCESS   read-only
       STATUS   mandatory
       DESCRIPTION
               "Count of valid frames received which were
               discarded (i.e., filtered) by the Forwarding
               Process."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.6.1.1.3"
       ::= { dot1dTpPortEntry 5 }






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   -- The Static (Destination-Address Filtering) Database

   -- Implementation of this group is optional.


   dot1dStaticTable OBJECT-TYPE
       SYNTAX  SEQUENCE OF Dot1dStaticEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "A table containing filtering information
               configured into the bridge by (local or network)
               management specifying the set of ports to which
               frames received from specific ports and containing
               specific destination addresses are allowed to be
               forwarded.  The value of zero in this table as the
               port number from which frames with a specific
               destination address are received, is used to
               specify all ports for which there is no specific
               entry in this table for that particular
               destination address.  Entries are valid for
               unicast and for group/broadcast addresses."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 6.7.2"
       ::= { dot1dStatic 1 }

   dot1dStaticEntry OBJECT-TYPE
       SYNTAX  Dot1dStaticEntry
       ACCESS  not-accessible
       STATUS  mandatory
       DESCRIPTION
               "Filtering information configured into the bridge
               by (local or network) management specifying the
               set of ports to which frames received from a
               specific port and containing a specific
               destination address are allowed to be forwarded."
       REFERENCE
               "P802.1d/D9, July 14,1989: Section 6.7.2"
       INDEX   { dot1dStaticAddress, dot1dStaticReceivePort }
       ::= { dot1dStaticTable 1 }

   Dot1dStaticEntry ::=
       SEQUENCE {
           dot1dStaticAddress
               MacAddress,
           dot1dStaticReceivePort
               INTEGER,
           dot1dStaticAllowedToGoTo



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               OCTET STRING,
           dot1dStaticStatus
               INTEGER
       }

   dot1dStaticAddress OBJECT-TYPE
       SYNTAX  MacAddress
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The destination MAC address in a frame to which
               this entry's filtering information applies.  This
               object can take the value of a unicast address, a
               group address or the broadcast address."
       REFERENCE
               "P802.1d/D9, July 14, 1989: Section 3.9.1, 3.9.2"
       ::= { dot1dStaticEntry 1 }

   dot1dStaticReceivePort OBJECT-TYPE
       SYNTAX  INTEGER
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "Either the value '0', or the port number of the
               port from which a frame must be received in order
               for this entry's filtering information to apply.
               A value of zero indicates that this entry applies
               on all ports of the bridge for which there is no
               other applicable entry."
       ::= { dot1dStaticEntry 2 }

   dot1dStaticAllowedToGoTo OBJECT-TYPE
       SYNTAX  OCTET STRING
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "The set of ports to which frames received from a
               specific port and destined for a specific MAC
               address, are allowed to be forwarded.  Each octet
               within the value of this object specifies a set of
               eight ports, with the first octet specifying ports
               1 through 8, the second octet specifying ports 9
               through 16, etc.  Within each octet, the most
               significant bit represents the lowest numbered
               port, and the least significant bit represents the
               highest numbered port.  Thus, each port of the
               bridge is represented by a single bit within the
               value of this object.  If that bit has a value of



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               '1' then that port is included in the set of
               ports; the port is not included if its bit has a
               value of '0'.  (Note that the setting of the bit
               corresponding to the port from which a frame is
               received is irrelevant.)"
       ::= { dot1dStaticEntry 3 }

   dot1dStaticStatus OBJECT-TYPE
       SYNTAX  INTEGER {
                   other(1),
                   invalid(2),
                   permanent(3),
                   deleteOnReset(4),
                   deleteOnTimeout(5)
               }
       ACCESS  read-write
       STATUS  mandatory
       DESCRIPTION
               "This object indicates the status of this entry.
                    other(1) - this entry is currently in use but
                         the conditions under which it will
                         remain so are different from each of the
                         following values.
                    invalid(2) - writing this value to the object
                         removes the corresponding entry.
                    permanent(3) - this entry is currently in use
                         and will remain so after the next reset
                         of the bridge.
                    deleteOnReset(4) - this entry is currently in
                         use and will remain so until the next
                         reset of the bridge.
                    deleteOnTimeout(5) - this entry is currently
                         in use and will remain so until it is
                         aged out."
       ::= { dot1dStaticEntry 4 }

   -- Traps for use by Bridges

   -- Traps for the Spanning Tree Protocol

   newRoot TRAP-TYPE
       ENTERPRISE  dot1dBridge
       DESCRIPTION
               "The newRoot trap indicates that the sending agent
               has become the new root of the Spanning Tree; the
               trap is sent by a bridge soon after its election
               as the new root, e.g., upon expiration of the
               Topology Change Timer immediately subsequent to



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               its election."
       ::= 1

   topologyChange TRAP-TYPE
       ENTERPRISE  dot1dBridge
       DESCRIPTION
               "A topologyChange trap is sent by a bridge when
               any of its configured ports transitions from the
               Learning state to the Forwarding state, or from
               the Forwarding state to the Blocking state.  The
               trap is not sent if a newRoot trap is sent for the
               same transition."
       ::= 2

   END

6.  Acknowledgments

   This document was produced on behalf of the Bridge Sub-Working Group
   of the SNMP Working Group of the Internet Engineering Task Force.
   Over the course of its deliberations, the working group received four
   separate documents for consideration as the basis for its work.  The
   first was submitted by Stan Froyd of Advanced Computer
   Communications; the second by Richard Fox of SynOptics; the third by
   Eric Decker of cisco Inc. and Keith McCloghrie of Hughes LAN Systems;
   and the fourth by Paul Langille and Anil Rijsinghani of Digital
   Equipment Corp. After considering the submissions, the working group
   chose to proceed with a document formed as a conjunction of the
   latter two submissions.  This document is the result.

   The authors wish to thank the members of the Bridge Working Group for
   their many comments and suggestions which improved this effort.  In
   particular, Fred Baker (chairman of the working group) of ACC, Steve
   Sherry of Xyplex, and Frank Kastenholz of Clearpoint Research Corp.
   Others members of the Bridge Working Group who contributed to this
   effort are:

        Bill Anderson, Mitre
        Karl Auerbach, Epilogue
        Fred Baker, ACC (chair)
        Terry Bradley, Wellfleet
        Ted Brunner, Bellcore
        Jeffrey Buffum, Apollo
        Chris ChioTasso, Fibronics
        Anthony Chung, HLS
        Chuck Davin, MIT-LCS
        Andy Davis, Spider
        Eric Decker, cisco



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        Nadya El-Afandi, Network Systems
        Gary Ellis,HP/Apollo
        Richard Fox, SynOptics
        Stan Froyd, ACC
        Frank Kastenholz, Clearpoint Research
        Shirnshon Kaufman,
        Jim Kinder, Fibercom
        Cheryl Krupczak,NCR
        Paul Langille, Digital
        Peter Lin,Vitalink
        Keith McCloghrie, HLS
        Donna McMaster, SynOptics
        Dave Perkins, 3Com
        Jim Reinstedler, Ungermann Bass
        Anil Rijsinghani, Digital
        Mark Schaefer, David Systems
        Steve Sherry, Xyplex
        Bob Stewart, Xyplex
        Emil Sturniolo,
        Kevin Synott, Retix
        Ian Thomas, Chipcom
        Maurice Turcott, Racal
        Fei Xu,

7.  References

   [1] Cerf, V., "IAB Recommendations for the Development of Internet
       Network Management Standards", RFC 1052, NRI, April 1988.

   [2]  Cerf, V., "Report of the Second Ad Hoc Network Management Review
       Group", RFC 1109, NRI, August 1989.

   [3] Rose M., and K. McCloghrie, "Structure and Identification of
       Management Information for TCP/IP-based internets", RFC 1155,
       Performance Systems International, Hughes LAN Systems, May 1990.

   [4] McCloghrie K., and M. Rose, "Management Information Base for
       Network Management of TCP/IP-based internets", RFC 1156, Hughes
       LAN Systems, Performance Systems International, May 1990.

   [5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple
       Network Management Protocol", RFC 1157, SNMP Research,
       Performance Systems International, Performance Systems
       International, MIT Laboratory for Computer Science, May 1990.

   [6] McCloghrie K., and M. Rose, Editors, "Management Information Base
       for Network Management of TCP/IP-based internets", RFC 1213,
       Performance Systems International, March 1991.



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   [7] Information processing systems - Open Systems Interconnection -
       Specification of Abstract Syntax Notation One (ASN.1),
       International Organization for Standardization, International
       Standard 8824, December 1987.

   [8] Information processing systems - Open Systems Interconnection -
       Specification of Basic Encoding Rules for Abstract Notation One
       (ASN.1), International Organization for Standardization,
       International Standard 8825, December 1987.

   [9] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions",
       RFC 1212, Performance Systems International, Hughes LAN Systems,
       March 1991.

  [10] Rose, M., Editor, "A Convention for Defining Traps for use with
       the SNMP", RFC 1215, Performance Systems International, March
       1991.

  [11] ANSI/IEEE Draft P802.1d/D9 MAC Bridges, "IEEE Project 802 Local
       and Metropolitan Area Networks", July 14, 1989.

  [12] I.B.M. Token Ring Architecture Reference.

  [13] ISO DIS 10038 MAC Bridges.

  [14] ANSI/IEEE P802.1x/P802.5x, "Proposed Draft Local Area Network
       Standard -- MAC Bridges, Source Routing Supplement", IEEE Project
       802, September 1990.

  [15] ANSI/IEEE 802.1y, "Source Routing Tutorial for End System
       Operation", September 1990.

8.  Security Considerations

   Security issues are not discussed in this memo.
















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9.  Authors' Addresses

   Eric B. Decker
   cisco Systems, Inc.
   1525 O'Brien Dr.
   Menlo Park, CA  94025

   Phone: (415) 326-1941
   Email: cire@cisco.com


   Paul Langille
   Digital Equipment Corporation
   Digital Drive, MK02-2/K03
   Merrimack, NH 03054

   Phone: (603) 884-4045
   EMail: langille@edwin.enet.dec.com


   Anil Rijsinghani
   Digital Equipment Corporation
   153 Taylor St.
   Littleton, MA 01460

   Phone: (508)952-3520
   EMail: anil@levers.enet.dec.com


   Keith McCloghrie
   Hughes LAN Systems
   1225 Charleston Road
   Mountain View, CA 94043

   Phone: (415) 966-7934
   EMail: kzm@hls.com















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