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