rfc1493.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

3.2.1.  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



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   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.

3.2.2.  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.

   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.





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3.3.  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.

4.  Changes from RFC 1286

          (1)  Updated all text to remove references to source route
               bridging where not applicable.  SR MIB will be a separate
               document.

          (2)  Removed dot1dSrPortTable.  Retained OID definition of
               dot1dSr.

          (3)  Updated all references of "draft P802.1d/D9" to "IEEE
               802.1D-1990".

          (4)  Updated bibliography.

          (5)  Added clarification to description of dot1dPortPathCost.

          (6)  Put recommended default in description of
               dot1dStaticAllowedToGoTo.

          (7)  Put recommended default in description of
               dot1dStaticStatus.

          (8)  Put recommended default in description of
               dot1dTpAgingTime.  Specified range of (10..1000000).

          (9)  Updated all port number syntaxes, when used as index, to
               use the range (1..65535).

          (10) Updated definition of dot1dTpPortInFrames and
               dot1dTpPortOutFrames.

          (11) Added text to the traps indicating that they are
               optional.

          (12) Clarified definition of dot1dStpForwardDelay.






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5.  Definitions

          BRIDGE-MIB DEFINITIONS ::= BEGIN

          IMPORTS
                     Counter, 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 n802.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:

          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).




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          -- 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-1990 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 }
          -- separately documented

          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
                      "IEEE 802.1D-1990: 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
                      "IEEE 802.1D-1990: Section 6.4.1.1.3"
              ::= { dot1dBase 2 }

          dot1dBaseType OBJECT-TYPE



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              SYNTAX  INTEGER {
                          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