NAME

ncStateByRa4Reachable - Verifying State Machine: RA vs. REACHABLE

TARGET

Host only

SYNOPSIS

  ncStateByRa4Reachable.seq [-tooloption ...] -p ncStateByRa4Reachable.def

INITIALIZATION

1. Set the state of neighbor cache entry to REACHABLE.
2. Cache either TN's LLA, or a bogus LLA

Cache a LLA of TN

  TN                 NUT
  ----------------------


  State: NONCE (for TN)


  ==== echo-request ===>
      src=TN's link-local
      dst=NUT's link-local


  State: INCOMPLETE (for TN)


  <=== multicast NS ====
      src=NUT's link-local
      dst=solicited-node[TN's link-local]
      target=TN's link-local
      SLLA=NUT's LLA
      timeout: RETRANS_TIMER * MAX_MULTICAST_SOLICIT


  ==== solicited NA ===>
      src=TN's link-local
      dst=NUT's link-local
      R=0, S=1, O=1
      target=TN's link-local
      TLLA=TN's LLA


  State: REACHABLE (for TN)

Cache a bogus LLA

  TN                 NUT
  ----------------------


  State: NONCE (for TN)


  ==== echo-request ===>
      src=TN's link-local
      dst=NUT's link-local


  State: INCOMPLETE (for TN)


  <=== multicast NS ====
      src=NUT's link-local
      dst=solicited-node[TN's link-local]
      target=TN's link-local
      SLLA=NUT's LLA
      timeout: RETRANS_TIMER * MAX_MULTICAST_SOLICIT


  ==== solicited NA ===>
      src=TN's link-local
      dst=NUT's link-local
      R=0, S=1, O=1
      target=TN's link-local
      TLLA=bogus LLA


  State: REACHABLE (for TN)

TEST PROCEDURE

ncStateByRa4Reachable verifies that state transition for a NUT in REACHABLE state when receiving a RA.

  TN               NUT
  ----------------------


  State: REACHABLE (for TN)


  ==== RA ===>
      src=TN's link
      dst=all-node
      RouterLifetime=600
      ReachableTime=0
      RetransTimer=0
      M=0, O=0
      w/o or w/ TLLA


  Judgment: Examining NUT's neighbor cache state

JUDGMENT

6.3.4.  Processing Received Router Advertisements


   After extracting information from the fixed part of the Router
   Advertisement message, the advertisement is scanned for valid
   options.  If the advertisement contains a Source Link-Layer Address
   option the link-layer address SHOULD be recorded in the Neighbor
   Cache entry for the router (creating an entry if necessary) and the
   IsRouter flag in the Neighbor Cache entry MUST be set to TRUE.  If no
   Source Link-Layer Address is included, but a corresponding Neighbor
   Cache entry exists, its IsRouter flag MUST be set to TRUE.  The
   IsRouter flag is used by Neighbor Unreachability Detection to
   determine when a router changes to being a host (i.e., no longer
   capable of forwarding packets).  If a Neighbor Cache entry is created
   for the router its reachability state MUST be set to STALE as
   specified in Section 7.3.3.  If a cache entry already exists and is
   updated with a different link-layer address the reachability state
   MUST also be set to STALE.


APPENDIX C: STATE MACHINE FOR THE REACHABILITY STATE


State           Event                   Action                New state


-               NS, RS, RA, Redirect    Create entry.         STALE


INCOMPLETE      NS, RS, RA, Redirect    Record link-layer     STALE
                                        address.  Send queued
                                        packets.


!INCOMPLETE     NS, RS, RA, Redirect    Update link-layer     STALE
                Different link-layer    address
                address than cached.


!INCOMPLETE     NS, RS, RA, Redirect    -                     unchanged
                Same link-layer
                address as cached.

  ========================+===================================+==============
  RA                      | Neighbor Cache                    | Comment
  ------------+-----------+-----------+-----------------------+
  Destination | TLLA      | Current   | New       | LLA       |
  ============+===========+===========+===========+===========+==============
  all-node    | none      | REACHABLE | unchanged | unchanged | Not mentioned
              |           |           |           |           | in RFC2461
  ------------+-----------+-----------+-----------+-----------+--------------
  all-node    | same      | REACHABLE | unchanged | unchanged |
  ------------+-----------+-----------+-----------+-----------+--------------
  all-node    | different | REACHABLE | STALE     | updated   |
  ============+===========+===========+===========+===========+==============



TERMINATION

  N/A



NOTE

  The test does not invoke any remote command.



SEE ALSO

  perldoc V6evalTool
  perldoc V6evalRemote