rfc2641.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

      Event

         This 4-octet field contains the number of the event.
         Valid values are as follows:

            1   A new neighbor switch was discovered on the
                specified port.
            2   The neighbor switch has gained the feature(s)
                specified in the Delta options mask.
            3   The neighbor switch has lost the feature(s)
                specified in the Delta options mask.
            4   The neighbor switch has timed out and is presumed
                down.
            5   The specified port is down.



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RFC 2641       Cabletron's VlanHello Protocol Version 4      August 1999


            6   The neighbor switch has been previously seen on a
                different port.  The specified port is the
                previous port.
            7   The specified port is being reassigned to another
                topology agent.  Event is generated by the current
                (old) agent.
            8   The port is looped -- that is, the Keepalive
                message was generated by the receiving switch.
            9   The port is crossed -- that is, a Keepalive message
                was received on a port not owned by this topology
                agent.
            10  The neighbor switch's functional level has changed.
            11  The neighbor switch is running an incompatible
                version of the protocol.
            12  Two-way communication with the neighbor switch has
                been lost.
            13  The neighbor switch's Keepalive message sequence
                number has been reset, indicating the switch
                itself has been reset.

   Delta options mask

      This 4-octet field contains a bit map specifying the feature(s)
      gained or lost by the neighbor switch (events 2 and 3 only).
      Valid values are as specified for the next field, Current options
      mask.

   Current options mask

      This 4-octet field contains a bit map specifying the features of
      the neighbor switch.  Bit assignments are as follows:

         1       (unused)
         2       The switch is a VLAN switch.
         4       The switch has link state capability.
         8       The switch has loop-free flood path capability.
         16      The switch has resolve capability.
         32      (unused)
         64      The switch has tag-based flood capability.
         128     The switch has tap capability.
         256     The switch has message connection capability.
         512     The switch has redundant access capability.
         1024    The switch is an isolated switch.
         4096    The switch is an uplink. (SFVLAN V1.8 only)
         8192    The switch is an uplink to core. (SFVLAN V1.8 only)
         16384   The port is an uplink port. (SFVLAN V1.8 only)
         32768   The port is an uplink flood port. (SFVLAN V1.8 only)




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RFC 2641       Cabletron's VlanHello Protocol Version 4      August 1999


   Port number

      This 4-octet field contains the logical number of the local port
      for which the event was generated.

   Port neighbor switch identifier

      This 10-octet field contains the internal identifier of the
      neighbor switch discovered on the port.  The identifier consists
      of the 6-octet physical (MAC) address of the neighbor switch,
      followed by the 4-octet logical port number (local to the neighbor
      switch) on which the neighbor was discovered.

   Port neighbor IP address

      This 4-octet field contains the Internet Protocol (IP) address of
      the neighbor switch.

   Neighbor chassis MAC address

      This 6-octet field contains the physical (MAC) address of the
      chassis of the neighbor switch.

   Neighbor chassis IP address

      This 4-octet field contains the Internet Protocol (IP) address of
      the chassis of the neighbor switch.

   Neighbor functional level

      This 4-octet field contains the functional level of the neighbor
      switch, as determined by the version level of the SecureFast VLAN
      software under which this switch is operating.  Valid values are
      as follows:

      1  The switch is running a version of SFVLAN prior to Version 1.8.
      2  The switch is running SFVLAN Version 1.8 or greater.

   Topology agent

      This 4-octet field contains a pointer to the topology agent that
      generated the event.  The pointer here can reference any of the
      topology agents that send Interswitch Keepalive messages -- that
      is, any agent running the VlanHello protocol.







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RFC 2641       Cabletron's VlanHello Protocol Version 4      August 1999


   Next event

      This 4-octet field contains a pointer to the next event relay
      structure in the list.

2.4 Timers

   The VlanHello protocol uses three timers.

   o  Send Hello timer.  The Send Hello timer is used to control the
      interval at which Interswitch Keepalive messages are sent.

   o  Aging timer.  The Aging Timer is used to detect when communication
      with a neighboring switch has been lost.

   o  Going to Access timer.  The Going to Access timer is used to
      synchronize the transition of a port state to Access and prevent a
      port from being prematurely designation as an Access port during
      network initialization.  If an Unknown port receives any packet
      other than an Interswitch Keepalive message, the port state is set
      to Going To Access.  If the switch receives an Interswitch
      Keepalive message over that port before the timer expires, the
      port state is changed to Network. Otherwise, when the timer
      expires, the port state is changed to Access.

3. InterSwitch Message Protocol

   The VlanHello protocol operates as part of the InterSwitch Message
   Protocol (ISMP) -- part of Cabletron's SecureFast VLAN (SFVLAN)
   product, as described in [IDsfvlan].  ISMP provides a consistent
   method of encapsulating and transmitting network control messages
   exchanged between SFVLAN switches.

   ISMP message packets are of variable length and have the following
   general structure:

   o  Frame header
   o  ISMP packet header
   o  ISMP message body












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3.1 Frame Header

   ISMP packets are encapsulated within an IEEE 802-compliant frame
   using a standard header as shown below:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   00 |                                                               |
      +      Destination address      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   04 |                               |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+        Source address         +
   08 |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   12 |             Type              |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   16 |                                                               |
      +                                                               +
      :                                                               :


   Destination address

      This 6-octet field contains the Media Access Control (MAC) address
      of the multicast channel over which all switches in the fabric
      receive ISMP packets.  The destination address fields of all ISMP
      packets contain a value of 01-00-1D-00-00-00.

   Source address

      This 6-octet field contains the physical (MAC) address of the
      switch originating the ISMP packet.

   Type

      This 2-octet field identifies the type of data carried within the
      frame.  The type field of ISMP packets contains the value 0x81FD.














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RFC 2641       Cabletron's VlanHello Protocol Version 4      August 1999


3.2 ISMP Packet Header

   The ISMP packet header consists of a variable number of octets, as
   shown below:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   00 |///////////////////////////////////////////////////////////////|
      ://////// Frame header /////////////////////////////////////////:
      +//////// (14 octets)  /////////+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   12 |///////////////////////////////|         ISMP Version          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   16 |       ISMP message type       |        Sequence number        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   20 |  Code length  |                                               |
      +-+-+-+-+-+-+-+-+                                               +
      |                        Authentication code                    |
      :                                                               :
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      :                                                               :


   Frame header

      This 14-octet field contains the frame header.

   ISMP Version

      This 2-octet field contains the version number of the InterSwitch
      Message Protocol to which this ISMP packet adheres.  The VlanHello
      protocol uses ISMP Version 3.0.

   ISMP message type

      This 2-octet field contains a value indicating which type of ISMP
      message is contained within the message body. VlanHello
      Interswitch Keepalive messages have a message type of 2.

   Sequence number

      This 2-octet field contains an internally generated sequence
      number used by the various protocol handlers for internal
      synchronization of messages.





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   Code length

      This 1-octet field contains the number of octets in the
      Authentication code field of the message.

   Authentication code

      This variable-length field contains an encoded value used for
      authentication of the ISMP message.

3.3 ISMP Message Body

   The ISMP message body is a variable-length field containing the
   actual data of the ISMP message.  The length and content of this
   field are determined by the value found in the message type field.