RFC4188

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Network Working Group K. Norseth, Ed. Request for Comments: 4188 L-3 Communications Obsoletes: 1493 E. Bell, Ed. Category: Standards Track 3Com Europe Limited

                                                      September 2005
           Definitions of Managed Objects for Bridges

Status of This Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2005).

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-1998 standard between Local Area Network (LAN) segments. Provisions are made for the support of transparent bridging. Provisions are also made so that these objects apply to bridges connected by subnetworks other than LAN segments.

The MIB module presented in this memo is a translation of the BRIDGE-MIB defined in RFC 1493 to the SMIv2 syntax.

This memo obsoletes RFC 1493.

The Internet-Standard Management Framework

For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 RFC3410.

Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 RFC2578, STD 58, RFC 2579 RFC2579 and STD 58, RFC 2580 RFC2580.

Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL", when they appear in this document, are to be interpreted as described in BCP 14, RFC 2119 RFC2119.

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 IEEE 802.1D specification [IEEE8021D]. This memo defines those objects needed for the management of a bridging entity that operates in the transparent mode, as well as some objects that apply to all types of bridges.

To be consistent with IAB directives and good engineering practices, an explicit attempt was made to keep this MIB module 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 that objects be essential for either fault or

  configuration management.

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

4. Limit the total number of objects.

5. Exclude objects that are simply derivable from others in this or

  other MIB modules.

6. Avoid causing critical sections to be heavily instrumented. The

  guideline that was followed is one counter per critical section
  per layer.

Structure of the MIB Module

Objects in this MIB module are arranged into subtrees. Each subtree is organized as a set of related objects. The overall structure and assignment of objects to their subtrees is shown below. Where appropriate, the corresponding IEEE 802.1D [IEEE8021D] 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
     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
     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 module for the indicated reasons.

IEEE 802.1D Object Disposition

Bridge.BridgeName Same as sysDescr (SNMPv2-MIB) Bridge.BridgeUpTime Same as sysUpTime (SNMPv2-MIB) Bridge.PortAddresses Same as ifPhysAddress (IF-MIB) BridgePort.PortName Same as ifDescr (IF-MIB) BridgePort.PortType Same as ifType (IF-MIB) BridgePort.RoutingType Derivable from the implemented

                               subtrees

SpanningTreeProtocol

   .BridgeIdentifier           Combination of dot1dStpPriority
                               and dot1dBaseBridgeAddress
   .TopologyChange             Since this is transitory, it
                               is not considered useful.

SpanningTreeProtocolPort

   .Uptime                     Same as ifLastChange (IF-MIB)
   .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
                               are not considered useful.
   .TransmissionPriorityName
   .OutboundUserPriority
   .OutboundAccessPriority

The dot1dBase Subtree

This subtree contains the objects that are applicable to all types of bridges.

The dot1dStp Subtree

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

The dot1dSr Subtree

This subtree contains the objects that describe the entity's state with respect to source route bridging. This subtree described in RFC 1525 RFC1525 is applicable only to source route bridging.

The dot1dTp Subtree

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

The dot1dStatic Subtree

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

Relationship to Other MIB Modules

As described above, some IEEE 802.1D management objects have not been included in this MIB module because they overlap with objects in other MIB modules that are applicable to a bridge implementing this MIB module.

Relationship to the SNMPv2-MIB

The SNMPv2-MIB RFC3418 defines objects that are generally applicable to managed devices. These objects apply to the device as a whole, irrespective of whether the device's sole functionality is bridging, or whether bridging is only a subset of the device's functionality.

As explained in Section 3.1, full support for the 802.1D management objects requires that the SNMPv2-MIB objects sysDescr and sysUpTime be implemented. Note that compliance with the current SNMPv2-MIB module requires additional objects and notifications to be implemented, as specified in RFC 3418 RFC3418.

Relationship to the IF-MIB

The IF-MIB RFC2863 defines managed objects for managing network interfaces. A network 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.

As explained in Section 3.1, full support for the 802.1D management objects requires that the IF-MIB objects ifIndex, ifType, ifDescr, ifPhysAddress, and ifLastChange are implemented. Note that compliance to the current IF-MIB module requires additional objects and notifications to be implemented as specified in RFC 2863 RFC2863.

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' subtree, 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 that are 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 functionalities 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 that exclusively performs bridging, all protocols would be considered as bridged, whereas in an entity that performs IP routing on IP datagrams and only bridges other protocols, only the non-IP data would be considered as having been bridged.

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

Definitions

BRIDGE-MIB DEFINITIONS ::= BEGIN

-- ---------------------------------------------------------- -- -- MIB for IEEE 802.1D devices -- ---------------------------------------------------------- -- IMPORTS

   MODULE-IDENTITY, OBJECT-TYPE, NOTIFICATION-TYPE,
   Counter32, Integer32, TimeTicks, mib-2
       FROM SNMPv2-SMI
   TEXTUAL-CONVENTION, MacAddress
       FROM SNMPv2-TC
   MODULE-COMPLIANCE, OBJECT-GROUP, NOTIFICATION-GROUP
       FROM SNMPv2-CONF
   InterfaceIndex FROM IF-MIB
   ;

dot1dBridge MODULE-IDENTITY

   LAST-UPDATED "200509190000Z"
   ORGANIZATION "IETF Bridge MIB Working Group"
   CONTACT-INFO
       "Email: [email protected]
                K.C. Norseth (Editor)
                L-3 Communications
           Tel: +1 801-594-2809
         Email: [email protected]
        Postal: 640 N. 2200 West.
                Salt Lake City, Utah 84116-0850
                Les Bell (Editor)
                3Com Europe Limited
         Phone: +44 1442 438025
         Email: [email protected]
        Postal: 3Com Centre, Boundary Way
                Hemel Hempstead
                Herts.  HP2 7YU
                UK
        Send comments to <[email protected]>"
   DESCRIPTION
       "The Bridge MIB module for managing devices that support
       IEEE 802.1D.
       Copyright (C) The Internet Society (2005).  This version of
       this MIB module is part of RFC 4188; see the RFC itself for
       full legal notices."
   REVISION     "200509190000Z"
   DESCRIPTION
        "Third revision, published as part of RFC 4188.
        The MIB module has been converted to SMIv2 format.
        Conformance statements have been added and some
        description and reference clauses have been updated.
        The object dot1dStpPortPathCost32 was added to
        support IEEE 802.1t and the permissible values of
        dot1dStpPriority and dot1dStpPortPriority have been
        clarified for bridges supporting IEEE 802.1t or
        IEEE 802.1w.
        The interpretation of dot1dStpTimeSinceTopologyChange
        has been clarified for bridges supporting the Rapid
        Spanning Tree Protocol (RSTP)."
   REVISION     "199307310000Z"
   DESCRIPTION
        "Second revision, published as part of RFC 1493."
   REVISION     "199112310000Z"
   DESCRIPTION
        "Initial revision, published as part of RFC 1286."
   ::= { mib-2 17 }

-- ---------------------------------------------------------- -- -- Textual Conventions -- ---------------------------------------------------------- --

BridgeId ::= TEXTUAL-CONVENTION

   STATUS      current
   DESCRIPTION
       "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)."
   SYNTAX      OCTET STRING (SIZE (8))

Timeout ::= TEXTUAL-CONVENTION

   DISPLAY-HINT "d"
   STATUS      current
   DESCRIPTION
       "A Spanning Tree Protocol (STP) timer in units of 1/100
       seconds.  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
       hundredths 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-1998 specifies a settable granularity of no more
       than one second for these timers.  To avoid ambiguity,
       a conversion algorithm is defined below for converting
       between the different units, which ensures a timer's
       value is not distorted by multiple conversions.
       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 nonzero]
           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)."
   SYNTAX      Integer32

-- ---------------------------------------------------------- -- -- subtrees in the Bridge MIB -- ---------------------------------------------------------- --

dot1dNotifications OBJECT IDENTIFIER ::= { dot1dBridge 0 }

dot1dBase OBJECT IDENTIFIER ::= { dot1dBridge 1 } dot1dStp OBJECT IDENTIFIER ::= { dot1dBridge 2 }

dot1dSr OBJECT IDENTIFIER ::= { dot1dBridge 3 } -- documented in RFC 1525

dot1dTp OBJECT IDENTIFIER ::= { dot1dBridge 4 } dot1dStatic OBJECT IDENTIFIER ::= { dot1dBridge 5 }

-- Subtrees used by Bridge MIB Extensions: -- pBridgeMIB MODULE-IDENTITY ::= { dot1dBridge 6 } -- qBridgeMIB MODULE-IDENTITY ::= { dot1dBridge 7 } -- Note that the practice of registering related MIB modules -- below dot1dBridge has been discouraged since there is no -- robust mechanism to track such registrations.

dot1dConformance OBJECT IDENTIFIER ::= { dot1dBridge 8 }

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

dot1dBaseBridgeAddress OBJECT-TYPE

   SYNTAX      MacAddress
   MAX-ACCESS  read-only
   STATUS      current
   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
       "IEEE 802.1D-1998: clauses 14.4.1.1.3 and 7.12.5"
   ::= { dot1dBase 1 }

dot1dBaseNumPorts OBJECT-TYPE

   SYNTAX      Integer32
   UNITS       "ports"
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The number of ports controlled by this bridging
       entity."
   REFERENCE
       "IEEE 802.1D-1998: clause 14.4.1.1.3"
   ::= { dot1dBase 2 }

dot1dBaseType OBJECT-TYPE

   SYNTAX      INTEGER {
                   unknown(1),
                   transparent-only(2),
                   sourceroute-only(3),
                   srt(4)
               }
   MAX-ACCESS  read-only
   STATUS      current
   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
   MAX-ACCESS  not-accessible
   STATUS      current
   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
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A list of information for each port of the bridge."
   REFERENCE
       "IEEE 802.1D-1998: clause 14.4.2, 14.6.1"
   INDEX  { dot1dBasePort }
   ::= { dot1dBasePortTable 1 }

Dot1dBasePortEntry ::=

   SEQUENCE {
       dot1dBasePort
           Integer32,
       dot1dBasePortIfIndex
           InterfaceIndex,
       dot1dBasePortCircuit
           OBJECT IDENTIFIER,
       dot1dBasePortDelayExceededDiscards
           Counter32,
       dot1dBasePortMtuExceededDiscards
           Counter32
   }

dot1dBasePort OBJECT-TYPE

   SYNTAX      Integer32 (1..65535)
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The port number of the port for which this entry
       contains bridge management information."
   ::= { dot1dBasePortEntry 1 }

dot1dBasePortIfIndex OBJECT-TYPE

   SYNTAX      InterfaceIndex
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The value of the instance of the ifIndex object,
       defined in IF-MIB, for the interface corresponding
       to this port."
   ::= { dot1dBasePortEntry 2 }

dot1dBasePortCircuit OBJECT-TYPE

   SYNTAX      OBJECT IDENTIFIER
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "For a port that (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      Counter32
   MAX-ACCESS  read-only
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 14.6.1.1.3"
   ::= { dot1dBasePortEntry 4 }

dot1dBasePortMtuExceededDiscards OBJECT-TYPE

   SYNTAX      Counter32
   MAX-ACCESS  read-only
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 14.6.1.1.3"
   ::= { dot1dBasePortEntry 5 }

-- ---------------------------------------------------------- -- -- the dot1dStp subtree -- ---------------------------------------------------------- -- -- Implementation of the dot1dStp subtree is optional. It is -- implemented by those bridges that support the Spanning Tree -- Protocol. -- ---------------------------------------------------------- --

dot1dStpProtocolSpecification OBJECT-TYPE

   SYNTAX      INTEGER {
                   unknown(1),
                   decLb100(2),
                   ieee8021d(3)
               }
   MAX-ACCESS  read-only
   STATUS      current
   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
       that are incompatible with the current version
       are released a new value will be defined."
   ::= { dot1dStp 1 }

dot1dStpPriority OBJECT-TYPE

   SYNTAX      Integer32 (0..65535)
   MAX-ACCESS  read-write
   STATUS      current
   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.
       On bridges supporting IEEE 802.1t or IEEE 802.1w,
       permissible values are 0-61440, in steps of 4096."
   REFERENCE
       "IEEE 802.1D-1998 clause 8.10.2, Table 8-4,
       IEEE 802.1t clause 8.10.2, Table 8-4, clause 14.3."
   ::= { dot1dStp 2 }

dot1dStpTimeSinceTopologyChange OBJECT-TYPE

   SYNTAX      TimeTicks
   UNITS       "centi-seconds"
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The time (in hundredths of a second) since the
       last time a topology change was detected by the
       bridge entity.
       For RSTP, this reports the time since the tcWhile
       timer for any port on this Bridge was nonzero."
   REFERENCE
       "IEEE 802.1D-1998 clause 14.8.1.1.,
       IEEE 802.1w clause 14.8.1.1."
   ::= { dot1dStp 3 }

dot1dStpTopChanges OBJECT-TYPE

   SYNTAX      Counter32
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The total number of topology changes detected by
       this bridge since the management entity was last
       reset or initialized."
   REFERENCE
       "IEEE 802.1D-1998 clause 14.8.1.1."
   ::= { dot1dStp 4 }

dot1dStpDesignatedRoot OBJECT-TYPE

   SYNTAX      BridgeId
   MAX-ACCESS  read-only
   STATUS      current
   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
       the Root Identifier parameter in all Configuration
       Bridge PDUs originated by this node."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.3.1"
   ::= { dot1dStp 5 }

dot1dStpRootCost OBJECT-TYPE

   SYNTAX      Integer32
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The cost of the path to the root as seen from
       this bridge."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.3.2"
   ::= { dot1dStp 6 }

dot1dStpRootPort OBJECT-TYPE

   SYNTAX      Integer32
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The port number of the port that offers the lowest
       cost path from this bridge to the root bridge."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.3.3"
   ::= { dot1dStp 7 }

dot1dStpMaxAge OBJECT-TYPE

   SYNTAX      Timeout
   UNITS       "centi-seconds"
   MAX-ACCESS  read-only
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 8.5.3.4"
   ::= { dot1dStp 8 }

dot1dStpHelloTime OBJECT-TYPE

   SYNTAX      Timeout
   UNITS       "centi-seconds"
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "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
       "IEEE 802.1D-1998: clause 8.5.3.5"
   ::= { dot1dStp 9 }

dot1dStpHoldTime OBJECT-TYPE

   SYNTAX      Integer32
   UNITS       "centi-seconds"
   MAX-ACCESS  read-only
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 8.5.3.14"
   ::= { dot1dStp 10 }

dot1dStpForwardDelay OBJECT-TYPE

   SYNTAX      Timeout
   UNITS       "centi-seconds"
   MAX-ACCESS  read-only
   STATUS      current
   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 each of the
       Listening and Learning states, which precede the
       Forwarding state.  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
       "IEEE 802.1D-1998: clause 8.5.3.6"
   ::= { dot1dStp 11 }

dot1dStpBridgeMaxAge OBJECT-TYPE

   SYNTAX      Timeout (600..4000)
   UNITS       "centi-seconds"
   MAX-ACCESS  read-write
   STATUS      current
   DESCRIPTION
       "The value that all bridges use for MaxAge when this
       bridge is acting as the root.  Note that 802.1D-1998
       specifies that the range for this parameter is related
       to the value of dot1dStpBridgeHelloTime.  The
       granularity of this timer is specified by 802.1D-1998 to
       be 1 second.  An agent may return a badValue error if a
       set is attempted to a value that is not a whole number
       of seconds."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.3.8"
   ::= { dot1dStp 12 }

dot1dStpBridgeHelloTime OBJECT-TYPE

   SYNTAX      Timeout (100..1000)
   UNITS       "centi-seconds"
   MAX-ACCESS  read-write
   STATUS      current
   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-1998 to be 1 second.  An
       agent may return a badValue error if a set is attempted
       to a value that is not a whole number of seconds."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.3.9"
   ::= { dot1dStp 13 }

dot1dStpBridgeForwardDelay OBJECT-TYPE

   SYNTAX      Timeout (400..3000)
   UNITS       "centi-seconds"
   MAX-ACCESS  read-write
   STATUS      current
   DESCRIPTION
       "The value that all bridges use for ForwardDelay when
       this bridge is acting as the root.  Note that
       802.1D-1998 specifies that the range for this parameter
       is related to the value of dot1dStpBridgeMaxAge.  The
       granularity of this timer is specified by 802.1D-1998 to
       be 1 second.  An agent may return a badValue error if a
       set is attempted to a value that is not a whole number
       of seconds."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.3.10"
   ::= { dot1dStp 14 }

-- ---------------------------------------------------------- -- -- The Spanning Tree Port Table -- ---------------------------------------------------------- --

dot1dStpPortTable OBJECT-TYPE

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

dot1dStpPortEntry OBJECT-TYPE

   SYNTAX      Dot1dStpPortEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   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
           Integer32,
       dot1dStpPortPriority
           Integer32,
       dot1dStpPortState
           INTEGER,
       dot1dStpPortEnable
           INTEGER,
       dot1dStpPortPathCost
           Integer32,
       dot1dStpPortDesignatedRoot
           BridgeId,
       dot1dStpPortDesignatedCost
           Integer32,
       dot1dStpPortDesignatedBridge
           BridgeId,
       dot1dStpPortDesignatedPort
           OCTET STRING,
       dot1dStpPortForwardTransitions
           Counter32,
       dot1dStpPortPathCost32
           Integer32
   }

dot1dStpPort OBJECT-TYPE

   SYNTAX      Integer32 (1..65535)
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The port number of the port for which this entry
       contains Spanning Tree Protocol management information."
   REFERENCE
       "IEEE 802.1D-1998: clause 14.8.2.1.2"
   ::= { dot1dStpPortEntry 1 }

dot1dStpPortPriority OBJECT-TYPE

   SYNTAX      Integer32 (0..255)
   MAX-ACCESS  read-write
   STATUS      current
   DESCRIPTION
       "The value of the priority field that 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.
       On bridges supporting IEEE 802.1t or IEEE 802.1w,
       permissible values are 0-240, in steps of 16."
   REFERENCE
       "IEEE 802.1D-1998 clause 8.10.2, Table 8-4,
       IEEE 802.1t clause 8.10.2, Table 8-4, clause 14.3."
   ::= { dot1dStpPortEntry 2 }

dot1dStpPortState OBJECT-TYPE

   SYNTAX      INTEGER {
                   disabled(1),
                   blocking(2),
                   listening(3),
                   learning(4),
                   forwarding(5),
                   broken(6)
               }
   MAX-ACCESS  read-only
   STATUS      current
   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 that are disabled (see dot1dStpPortEnable), this
       object will have a value of disabled(1)."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.5.2"
   ::= { dot1dStpPortEntry 3 }

dot1dStpPortEnable OBJECT-TYPE

   SYNTAX      INTEGER {
                   enabled(1),
                   disabled(2)
               }
   MAX-ACCESS  read-write
   STATUS      current
   DESCRIPTION
       "The enabled/disabled status of the port."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.5.2"
   ::= { dot1dStpPortEntry 4 }

dot1dStpPortPathCost OBJECT-TYPE

   SYNTAX      Integer32 (1..65535)
   MAX-ACCESS  read-write
   STATUS      current
   DESCRIPTION
       "The contribution of this port to the path cost of
       paths towards the spanning tree root which include
       this port.  802.1D-1998 recommends that the default
       value of this parameter be in inverse proportion to
       the speed of the attached LAN.
       New implementations should support dot1dStpPortPathCost32.
       If the port path costs exceeds the maximum value of this
       object then this object should report the maximum value,
       namely 65535.  Applications should try to read the
       dot1dStpPortPathCost32 object if this object reports
       the maximum value."
   REFERENCE "IEEE 802.1D-1998: clause 8.5.5.3"
       ::= { dot1dStpPortEntry 5 }

dot1dStpPortDesignatedRoot OBJECT-TYPE

   SYNTAX      BridgeId
   MAX-ACCESS  read-only
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 8.5.5.4"
   ::= { dot1dStpPortEntry 6 }

dot1dStpPortDesignatedCost OBJECT-TYPE

   SYNTAX      Integer32
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The path cost of the Designated Port of the segment
       connected to this port.  This value is compared to the
       Root Path Cost field in received bridge PDUs."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.5.5"
   ::= { dot1dStpPortEntry 7 }

dot1dStpPortDesignatedBridge OBJECT-TYPE

   SYNTAX      BridgeId
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The Bridge Identifier of the bridge that this
       port considers to be the Designated Bridge for
       this port's segment."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.5.6"
   ::= { dot1dStpPortEntry 8 }

dot1dStpPortDesignatedPort OBJECT-TYPE

   SYNTAX      OCTET STRING (SIZE (2))
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The Port Identifier of the port on the Designated
       Bridge for this port's segment."
   REFERENCE
       "IEEE 802.1D-1998: clause 8.5.5.7"
   ::= { dot1dStpPortEntry 9 }

dot1dStpPortForwardTransitions OBJECT-TYPE

   SYNTAX      Counter32
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The number of times this port has transitioned
       from the Learning state to the Forwarding state."
   ::= { dot1dStpPortEntry 10 }

dot1dStpPortPathCost32 OBJECT-TYPE

   SYNTAX      Integer32 (1..200000000)
   MAX-ACCESS  read-write
   STATUS      current
   DESCRIPTION
       "The contribution of this port to the path cost of
       paths towards the spanning tree root which include
       this port.  802.1D-1998 recommends that the default
       value of this parameter be in inverse proportion to
       the speed of the attached LAN.
       This object replaces dot1dStpPortPathCost to support
       IEEE 802.1t."
   REFERENCE
       "IEEE 802.1t clause 8.10.2, Table 8-5."
   ::= { dot1dStpPortEntry 11 }

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

dot1dTpLearnedEntryDiscards OBJECT-TYPE

   SYNTAX      Counter32
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The total number of Forwarding Database entries that
       have been or would have been learned, but have been
       discarded due to a lack of storage space in the
       Forwarding Database.  If this counter is increasing, it
       indicates that the Forwarding Database is regularly
       becoming full (a condition that has unpleasant
       performance effects 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
       "IEEE 802.1D-1998: clause 14.7.1.1.3"
   ::= { dot1dTp 1 }

dot1dTpAgingTime OBJECT-TYPE

   SYNTAX      Integer32 (10..1000000)
   UNITS       "seconds"
   MAX-ACCESS  read-write
   STATUS      current
   DESCRIPTION
       "The timeout period in seconds for aging out
       dynamically-learned forwarding information.
       802.1D-1998 recommends a default of 300 seconds."
   REFERENCE
       "IEEE 802.1D-1998: clause 14.7.1.1.3"
   ::= { dot1dTp 2 }

-- ---------------------------------------------------------- -- -- The Forwarding Database for Transparent Bridges -- ---------------------------------------------------------- --

dot1dTpFdbTable OBJECT-TYPE

   SYNTAX      SEQUENCE OF Dot1dTpFdbEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   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
   MAX-ACCESS  not-accessible
   STATUS      current
   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
           MacAddress,
       dot1dTpFdbPort
           Integer32,
       dot1dTpFdbStatus
           INTEGER
   }

dot1dTpFdbAddress OBJECT-TYPE

   SYNTAX      MacAddress
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "A unicast MAC address for which the bridge has
       forwarding and/or filtering information."
   REFERENCE
       "IEEE 802.1D-1998: clause 7.9.1, 7.9.2"
   ::= { dot1dTpFdbEntry 1 }

dot1dTpFdbPort OBJECT-TYPE

   SYNTAX      Integer32
   MAX-ACCESS  read-only
   STATUS      current
   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)
               }
   MAX-ACCESS  read-only
   STATUS      current
   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 no 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
   MAX-ACCESS  not-accessible
   STATUS      current
   DESCRIPTION
       "A table that contains information about every port that
       is associated with this transparent bridge."
   ::= { dot1dTp 4 }

dot1dTpPortEntry OBJECT-TYPE

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

Dot1dTpPortEntry ::=

   SEQUENCE {
       dot1dTpPort
           Integer32,
       dot1dTpPortMaxInfo
           Integer32,
       dot1dTpPortInFrames
           Counter32,
       dot1dTpPortOutFrames
           Counter32,
       dot1dTpPortInDiscards
           Counter32
   }

dot1dTpPort OBJECT-TYPE

   SYNTAX      Integer32 (1..65535)
   MAX-ACCESS  read-only
   STATUS      current
   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      Integer32
   UNITS       "bytes"
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "The maximum size of the INFO (non-MAC) field that
       this port will receive or transmit."
   ::= { dot1dTpPortEntry 2 }

dot1dTpPortInFrames OBJECT-TYPE

   SYNTAX      Counter32
   UNITS       "frames"
   MAX-ACCESS  read-only
   STATUS      current
   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, including
       bridge management frames."
   REFERENCE
       "IEEE 802.1D-1998: clause 14.6.1.1.3"
   ::= { dot1dTpPortEntry 3 }

dot1dTpPortOutFrames OBJECT-TYPE

   SYNTAX      Counter32
   UNITS       "frames"
   MAX-ACCESS  read-only
   STATUS      current
   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, including
       bridge management frames."
   REFERENCE
       "IEEE 802.1D-1998: clause 14.6.1.1.3"
   ::= { dot1dTpPortEntry 4 }

dot1dTpPortInDiscards OBJECT-TYPE

   SYNTAX      Counter32
   UNITS       "frames"
   MAX-ACCESS  read-only
   STATUS      current
   DESCRIPTION
       "Count of received valid frames that were discarded
       (i.e., filtered) by the Forwarding Process."
   REFERENCE
       "IEEE 802.1D-1998: clause 14.6.1.1.3"
   ::= { dot1dTpPortEntry 5 }

-- ---------------------------------------------------------- --

-- The Static (Destination-Address Filtering) Database -- ---------------------------------------------------------- -- -- Implementation of this subtree is optional. -- ---------------------------------------------------------- --

dot1dStaticTable OBJECT-TYPE

   SYNTAX      SEQUENCE OF Dot1dStaticEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 14.7.2"
   ::= { dot1dStatic 1 }

dot1dStaticEntry OBJECT-TYPE

   SYNTAX      Dot1dStaticEntry
   MAX-ACCESS  not-accessible
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 14.7.2"
   INDEX   { dot1dStaticAddress, dot1dStaticReceivePort }
   ::= { dot1dStaticTable 1 }

Dot1dStaticEntry ::=

   SEQUENCE {
       dot1dStaticAddress       MacAddress,
       dot1dStaticReceivePort   Integer32,
       dot1dStaticAllowedToGoTo OCTET STRING,
       dot1dStaticStatus        INTEGER
   }

dot1dStaticAddress OBJECT-TYPE

   SYNTAX      MacAddress
   MAX-ACCESS  read-create
   STATUS      current
   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
       "IEEE 802.1D-1998: clause 7.9.1, 7.9.2"
   ::= { dot1dStaticEntry 1 }

dot1dStaticReceivePort OBJECT-TYPE

   SYNTAX      Integer32 (0..65535)
   MAX-ACCESS  read-create
   STATUS      current
   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 (SIZE (0..512))
   MAX-ACCESS  read-create
   STATUS      current
   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 '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.)  The
       default value of this object is a string of ones of
       appropriate length.
       The value of this object may exceed the required minimum
       maximum message size of some SNMP transport (484 bytes,
       in the case of SNMP over UDP, see RFC 3417, section 3.2).
       SNMP engines on bridges supporting a large number of
       ports must support appropriate maximum message sizes."
   ::= { dot1dStaticEntry 3 }

dot1dStaticStatus OBJECT-TYPE

   SYNTAX      INTEGER {
                   other(1),
                   invalid(2),
                   permanent(3),
                   deleteOnReset(4),
                   deleteOnTimeout(5)
               }
   MAX-ACCESS  read-create
   STATUS      current
   DESCRIPTION
       "This object indicates the status of this entry.
       The default value is permanent(3).
           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 }

-- ---------------------------------------------------------- -- -- Notifications for use by Bridges -- ---------------------------------------------------------- -- -- Notifications for the Spanning Tree Protocol -- ---------------------------------------------------------- --

newRoot NOTIFICATION-TYPE

   -- OBJECTS     { }
   STATUS      current
   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 its election.  Implementation
       of this trap is optional."
   ::= { dot1dNotifications 1 }

topologyChange NOTIFICATION-TYPE

   -- OBJECTS     { }
   STATUS      current
   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.  Implementation of
       this trap is optional."
   ::= { dot1dNotifications 2 }

-- ---------------------------------------------------------- -- -- IEEE 802.1D MIB - Conformance Information -- ---------------------------------------------------------- --

dot1dGroups OBJECT IDENTIFIER ::= { dot1dConformance 1 } dot1dCompliances OBJECT IDENTIFIER ::= { dot1dConformance 2 }

-- ---------------------------------------------------------- -- -- units of conformance -- ---------------------------------------------------------- --

-- ---------------------------------------------------------- -- -- the dot1dBase group -- ---------------------------------------------------------- --

dot1dBaseBridgeGroup OBJECT-GROUP

   OBJECTS {
       dot1dBaseBridgeAddress,
       dot1dBaseNumPorts,
       dot1dBaseType
   }
   STATUS      current
   DESCRIPTION
       "Bridge level information for this device."
   ::= { dot1dGroups 1 }

dot1dBasePortGroup OBJECT-GROUP

   OBJECTS {
       dot1dBasePort,
       dot1dBasePortIfIndex,
       dot1dBasePortCircuit,
       dot1dBasePortDelayExceededDiscards,
       dot1dBasePortMtuExceededDiscards
   }
   STATUS      current
   DESCRIPTION
       "Information for each port on this device."
   ::= { dot1dGroups 2 }

-- ---------------------------------------------------------- -- -- the dot1dStp group -- ---------------------------------------------------------- --

dot1dStpBridgeGroup OBJECT-GROUP

   OBJECTS {
       dot1dStpProtocolSpecification,
       dot1dStpPriority,
       dot1dStpTimeSinceTopologyChange,
       dot1dStpTopChanges,
       dot1dStpDesignatedRoot,
       dot1dStpRootCost,
       dot1dStpRootPort,
       dot1dStpMaxAge,
       dot1dStpHelloTime,
       dot1dStpHoldTime,
       dot1dStpForwardDelay,
       dot1dStpBridgeMaxAge,
       dot1dStpBridgeHelloTime,
       dot1dStpBridgeForwardDelay
   }
   STATUS      current
   DESCRIPTION
       "Bridge level Spanning Tree data for this device."
   ::= { dot1dGroups 3 }

dot1dStpPortGroup OBJECT-GROUP

   OBJECTS {
       dot1dStpPort,
       dot1dStpPortPriority,
       dot1dStpPortState,
       dot1dStpPortEnable,
       dot1dStpPortPathCost,
       dot1dStpPortDesignatedRoot,
       dot1dStpPortDesignatedCost,
       dot1dStpPortDesignatedBridge,
       dot1dStpPortDesignatedPort,
       dot1dStpPortForwardTransitions
   }
   STATUS      current
   DESCRIPTION
       "Spanning Tree data for each port on this device."
   ::= { dot1dGroups 4 }

dot1dStpPortGroup2 OBJECT-GROUP

   OBJECTS {
       dot1dStpPort,
       dot1dStpPortPriority,
       dot1dStpPortState,
       dot1dStpPortEnable,
       dot1dStpPortDesignatedRoot,
       dot1dStpPortDesignatedCost,
       dot1dStpPortDesignatedBridge,
       dot1dStpPortDesignatedPort,
       dot1dStpPortForwardTransitions,
       dot1dStpPortPathCost32
   }
   STATUS      current
   DESCRIPTION
       "Spanning Tree data for each port on this device."
   ::= { dot1dGroups 5 }

dot1dStpPortGroup3 OBJECT-GROUP

   OBJECTS {
       dot1dStpPortPathCost32
   }
   STATUS      current
   DESCRIPTION
       "Spanning Tree data for devices supporting 32-bit
        path costs."
   ::= { dot1dGroups 6 }

-- ---------------------------------------------------------- -- -- the dot1dTp group -- ---------------------------------------------------------- --

dot1dTpBridgeGroup OBJECT-GROUP

   OBJECTS {
       dot1dTpLearnedEntryDiscards,
       dot1dTpAgingTime
   }
   STATUS      current
   DESCRIPTION
       "Bridge level Transparent Bridging data."
   ::= { dot1dGroups 7 }

dot1dTpFdbGroup OBJECT-GROUP

   OBJECTS {
       dot1dTpFdbAddress,
       dot1dTpFdbPort,
       dot1dTpFdbStatus
   }
   STATUS      current
   DESCRIPTION
       "Filtering Database information for the Bridge."
   ::= { dot1dGroups 8 }

dot1dTpGroup OBJECT-GROUP

   OBJECTS {
       dot1dTpPort,
       dot1dTpPortMaxInfo,
       dot1dTpPortInFrames,
       dot1dTpPortOutFrames,
       dot1dTpPortInDiscards
   }
   STATUS      current
   DESCRIPTION
       "Dynamic Filtering Database information for each port of
       the Bridge."
   ::= { dot1dGroups 9 }

-- ---------------------------------------------------------- -- -- The Static (Destination-Address Filtering) Database -- ---------------------------------------------------------- --

dot1dStaticGroup OBJECT-GROUP

   OBJECTS {
       dot1dStaticAddress,
       dot1dStaticReceivePort,
       dot1dStaticAllowedToGoTo,
       dot1dStaticStatus
   }
   STATUS      current
   DESCRIPTION
       "Static Filtering Database information for each port of
       the Bridge."
   ::= { dot1dGroups 10 }

-- ---------------------------------------------------------- -- -- The Trap Notification Group -- ---------------------------------------------------------- --

dot1dNotificationGroup NOTIFICATION-GROUP

   NOTIFICATIONS {
       newRoot,
       topologyChange
   }
   STATUS      current
   DESCRIPTION
       "Group of objects describing notifications (traps)."
   ::= { dot1dGroups 11 }

-- ---------------------------------------------------------- -- -- compliance statements -- ---------------------------------------------------------- --

bridgeCompliance1493 MODULE-COMPLIANCE

   STATUS      current
   DESCRIPTION
       "The compliance statement for device support of bridging
       services, as per RFC1493."
   MODULE
       MANDATORY-GROUPS {
           dot1dBaseBridgeGroup,
           dot1dBasePortGroup
       }
   GROUP   dot1dStpBridgeGroup
   DESCRIPTION
       "Implementation of this group is mandatory for bridges
       that support the Spanning Tree Protocol."
   GROUP   dot1dStpPortGroup
   DESCRIPTION
       "Implementation of this group is mandatory for bridges
       that support the Spanning Tree Protocol."
   GROUP   dot1dTpBridgeGroup
   DESCRIPTION
       "Implementation of this group is mandatory for bridges
       that support the transparent bridging mode.  A
       transparent or SRT bridge will implement this group."
   GROUP   dot1dTpFdbGroup
   DESCRIPTION
       "Implementation of this group is mandatory for bridges
       that support the transparent bridging mode.  A
       transparent or SRT bridge will implement this group."
   GROUP   dot1dTpGroup
   DESCRIPTION
       "Implementation of this group is mandatory for bridges
       that support the transparent bridging mode.  A
       transparent or SRT bridge will implement this group."
   GROUP   dot1dStaticGroup
   DESCRIPTION
       "Implementation of this group is optional."
   GROUP dot1dNotificationGroup
   DESCRIPTION
       "Implementation of this group is optional."
   ::= { dot1dCompliances 1 }

bridgeCompliance4188 MODULE-COMPLIANCE

   STATUS      current
   DESCRIPTION
       "The compliance statement for device support of bridging
       services.  This supports 32-bit Path Cost values and the
       more restricted bridge and port priorities, as per IEEE
       802.1t.
       Full support for the 802.1D management objects requires that
       the SNMPv2-MIB RFC3418 objects sysDescr, and sysUpTime, as
       well as the IF-MIB RFC2863 objects ifIndex, ifType,
       ifDescr, ifPhysAddress, and ifLastChange are implemented."
   MODULE
       MANDATORY-GROUPS {
           dot1dBaseBridgeGroup,
           dot1dBasePortGroup
       }
   GROUP   dot1dStpBridgeGroup
   DESCRIPTION
       "Implementation of this group is mandatory for
       bridges that support the Spanning Tree Protocol."
   OBJECT dot1dStpPriority
   SYNTAX Integer32 (0|4096|8192|12288|16384|20480|24576
                    |28672|32768|36864|40960|45056|49152
                    |53248|57344|61440)
   DESCRIPTION
       "The possible values defined by IEEE 802.1t."
   GROUP   dot1dStpPortGroup2
   DESCRIPTION
       "Implementation of this group is mandatory for
       bridges that support the Spanning Tree Protocol."
   GROUP   dot1dStpPortGroup3
   DESCRIPTION
       "Implementation of this group is mandatory for bridges
        that support the Spanning Tree Protocol and 32-bit path
        costs.  In particular, this includes devices supporting
        IEEE 802.1t and IEEE 802.1w."
   OBJECT dot1dStpPortPriority
   SYNTAX Integer32 (0|16|32|48|64|80|96|112|128
                    |144|160|176|192|208|224|240)
   DESCRIPTION
       "The possible values defined by IEEE 802.1t."
   GROUP   dot1dTpBridgeGroup
   DESCRIPTION
       "Implementation of this group is mandatory for
       bridges that support the transparent bridging
       mode.  A transparent or SRT bridge will implement
       this group."
   GROUP   dot1dTpFdbGroup
   DESCRIPTION
       "Implementation of this group is mandatory for
       bridges that support the transparent bridging
       mode.  A transparent or SRT bridge will implement
       this group."
   GROUP   dot1dTpGroup
   DESCRIPTION
       "Implementation of this group is mandatory for
       bridges that support the transparent bridging
       mode.  A transparent or SRT bridge will implement
       this group."
   GROUP   dot1dStaticGroup
   DESCRIPTION
       "Implementation of this group is optional."
   GROUP dot1dNotificationGroup
   DESCRIPTION
       "Implementation of this group is optional."
   ::= { dot1dCompliances 2 }

END

IANA Considerations

The MIB module in this document uses the following IANA-assigned OBJECT IDENTIFIER values that are recorded in the SMI Numbers registry:

  Descriptor        OBJECT IDENTIFIER value
  ----------        -----------------------
  dot1dBridge       { mib-2 17 }

Security Considerations

There are a number of management objects defined in this MIB module that have a MAX-ACCESS clause of read-write and/or read-create. Such objects may be considered sensitive or vulnerable in some network environments. The support for SET operations in a non-secure environment without proper protection can have a negative effect on network operations.

Some of the readable objects in this MIB module (i.e., objects with a MAX-ACCESS other than not-accessible) may be considered sensitive or vulnerable in some network environments. It is thus important to control even GET and/or NOTIFY access to these objects and possibly to even encrypt the values of these objects when sending them over the network via SNMP.

These are the tables and objects and their sensitivity/vulnerability:

o The writable objects dot1dStpPriority, dot1dStpBridgeMaxAge,

  dot1dStpBridgeHelloTime, dot1dStpBridgeForwardDelay,
  dot1dStpPortPriority, dot1dStpPortEnable, dot1dStpPortPathCost,
  and dot1dStpPortPathCost32 influence the spanning tree protocol.
  Unauthorized write access to these objects can cause the spanning
  tree protocol to compute other default topologies or it can change
  the speed in which the spanning tree protocol reacts to failures.

o The writable object dot1dTpAgingTime controls how fast

  dynamically-learned forwarding information is aged out.  Setting
  this object to a large value may simplify forwarding table
  overflow attacks.

o The writable dot1dStaticTable provides a filtering mechanism

  controlling to which ports frames originating from a specific
  source may be forwarded.  Write access to this table can be used
  to turn provisioned filtering off or to add filters to prevent
  rightful use of the network.

o The readable objects defined in the BRIDGE-MIB module provide

  information about the topology of a bridged network and the
  attached active stations.  The addresses listed in the
  dot1dTpFdbTable usually reveal information about the manufacturer
  of the MAC hardware, which can be useful information for mounting
  other specific attacks.

o The two notifications newRoot and topologyChange are emitted

  during spanning tree computation and may trigger management
  systems to inspect the status of bridges and to recompute internal
  topology information.  Hence, forged notifications may cause
  management systems to perform unnecessary computations and to
  generate additional SNMP traffic directed to the bridges in a
  network.  Therefore, forged notifications may be part of a denial
  of service attack.

SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example by using IPSec), even then, there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB module.

It is RECOMMENDED that implementers consider the security features as provided by the SNMPv3 framework (see RFC3410, section 8), including full support for the SNMPv3 cryptographic mechanisms (for authentication and privacy).

Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security. It is then a customer/operator responsibility to ensure that the SNMP entity giving access to an instance of this MIB module is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them.

Acknowledgements

The MIB module presented in this memo is a translation of the BRIDGE-MIB defined in RFC1493 to the SMIv2 syntax. The original authors of the SMIv1 module were E. Decker, P. Langille, A. Rijsinghani, and K. McCloghrie. Further acknowledgement is given to the members of the original Bridge Working Group in RFC1493.

This document was produced on behalf of the Bridge MIB Working Group in the Operations and Management area of the Internet Engineering Task Force. The editors wish to thank the members of the Bridge MIB Working Group, especially Mike MacFadden, John Flick, and Bert Visscher for their many comments and suggestions that improved this

effort. Juergen Schoenwaelder helped in finalizing the document for publication.

Contact Information

The original version of this document was the result of significant work by four major contributors:

  E. Decker
  P. Langille
  A. Rijsinghan
  Accton Technology Corporation
  5 Mount Royal Ave
  Marlboro, MA 01752
  USA
  K. McCloghrie
  Cisco Systems, Inc.
  170 West Tasman Drive
  San Jose, CA 95134
  USA

The conversion to the SMIv2 format is based on work done by the following two contributors:

  Kenyon C. Norseth
  L-3 Communications
  640 N. 2200 West
  Salt Lake City, Utah 84116-0850
  USA
  E. Bell
  3Com Europe Limited
  3Com Centre, Boundary Way
  Hemel Hempstead Herts. HP2 7YU
  UK

Changes from RFC 1493

The following changes have been made from RFC 1493.

1. Translated the MIB definitions to use SMIv2. This includes the

  introduction of conformance statements.  ASN.1 type definitions
  have been converted into textual-conventions and several UNITS
  clauses were added.

2. The object dot1dStpPortPathCost32 was added to support IEEE

  802.1t.

3. Permissible values for dot1dStpPriority and dot1dStpPortPriority

  have been clarified for bridges supporting IEEE 802.1t or IEEE
  802.1w.

4. Interpretation of dot1dStpTimeSinceTopologyChange has been

  clarified for bridges supporting the rapid spanning tree protocol
  (RSTP).

5. Updated the introductory boilerplate text, the security

  considerations section, and the references to comply with the
  current IETF standards and guidelines.

6. Updated references to point to newer IEEE 802.1d documents.

7. Additions and clarifications in various description clauses.

10. References

10.1 Normative References

RFC2119 Bradner, S., "Key words for use in RFCs to Indicate

           Requirement Levels", BCP 14, RFC 2119, March 1997.

RFC2578 McCloghrie, K., Perkins, D., and J. Schoenwaelder,

           "Structure of Management Information Version 2 (SMIv2)",
           STD 58, RFC 2578, April 1999.

RFC2579 McCloghrie, K., Perkins, D., and J. Schoenwaelder,

           "Textual Conventions for SMIv2", STD 58, RFC 2579, April
           1999.

RFC2580 McCloghrie, K., Perkins, D., and J. Schoenwaelder,

           "Conformance Statements for SMIv2", STD 58, RFC 2580,
           April 1999.

RFC3418 Presuhn, R., "Management Information Base (MIB) for the

           Simple Network Management Protocol (SNMP)", STD 62, RFC
           3418, December 2002.

RFC2863 McCloghrie, K. and F. Kastenholz, "The Interfaces Group

           MIB", RFC 2863, June 2000.

[IEEE8021D] IEEE Project 802 Local and Metropolitan Area Networks,

           "ANSI/IEEE Standard 802.1D-1998 MAC Bridges", March 1998.

10.2 Informative References

RFC3410 Case, J., Mundy, R., Partain, D., and B. Stewart,

           "Introduction and Applicability Statements for Internet-
           Standard Management Framework", RFC 3410, December 2002.

RFC1493 Decker, E., Langille, P., Rijsinghani, A., and K.

           McCloghrie, "Definitions of Managed Objects for Bridges",
           RFC 1493, July 1993.

RFC1525 Decker, E., McCloghrie, K., Langille, P., and A.

           Rijsinghani, "Definitions of Managed Objects for Source
           Routing Bridges", RFC 1525, September 1993.

Authors' Addresses

Kenyon C. Norseth (editor) L-3 Communications 640 N. 2200 West Salt Lake City, Utah 84116-0850 USA

Phone: +1 801-594-2809 EMail: [email protected]

E. Bell (editor) 3Com Europe Limited 3Com Centre, Boundary Way Hemel Hempstead Herts. HP2 7YU UK

Phone: +44 1442 438025 EMail: [email protected]

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