ncStateByNa4Probe - Verifying State Machine: NA vs. PROBE
Host and Router
ncStateByNa4Probe.seq [-tooloption ...] -p ncStateByNa4Probe.def
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 w/ SLLA timeout: RETRANS_TIMER * MAX_MULTICAST_SOLICIT
==== solicited NA ===> src=TN's link-local dst=NUT's link-local target=TN's link-local TLLA=TN's LLA
State: REACHABLE (for TN)
<=== echo-reply ==== src=NUT's link-local dst=TN's link-local timeout: 2 sec
Wait (REACHABLE_TIME * MAX_RANDOM_FACTOR)
State: STALE (for TN)
==== echo-request ===> src=TN's link-local dst=NUT's link-local
<=== echo-reply ==== src=NUT's link-local dst=TN's link-local timeout: 2 sec
State: DELAY (for TN)
Wait (DELAY_FIRST_PROBE_TIME)
State: PROBE (for 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 w/ SLLA timeout: RETRANS_TIMER * MAX_MULTICAST_SOLICIT
==== solicited NA ===> src=TN's link-local dst=NUT's link-local target=TN's link-local TLLA=a bogus LLA
State: REACHABLE (for TN)
<=== echo-reply ==== src=NUT's link-local dst=TN's link-local timeout: 2 sec
Wait (REACHABLE_TIME * MAX_RANDOM_FACTOR)
State: STALE (for TN)
==== echo-request ===> src=TN's link-local dst=NUT's link-local
<=== echo-reply ==== src=NUT's link-local dst=TN's link-local timeout: 2 sec
State: DELAY (for TN)
Wait (DELAY_FIRST_PROBE_TIME)
State: PROBE
ncStateByNa4Probe verifies that state transition for a NUT in PROBE state when receiving a NA.
TN NUT ----------------------
State: PROBE (for TN)
==== NA ===> src=TN's link-local dst=NUT's link-local or all-node w/o or w/ TLLA r=0, s=0/1, o=0/1
Judgment: Examining NUT's neighbor cache state
7.2.5. Receipt of Neighbor Advertisements
IF(State != INCOMPLETE) { If the target's Neighbor Cache entry is in any state other than INCOMPLETE when the advertisement is received, processing becomes quite a bit more complex. IF(Override==0 && TLLA!=LLA) { If the Override flag is clear and the supplied link-layer address differs from that in the cache, then one of two actions takes place: IF(REACHABLE) { if the state of the entry is REACHABLE, set it to STALE, but do not update the entry in any other way; }ELSE { otherwise, the received advertisement should be ignored and must not update the cache. } } ELSIF(Override==1 || (Override==0 && TLLA==LLA) || TLLA==NULL) { If the Override flag is set, both the Override flag is clear and the supplied link-layer address is the same as that in the cache, or no Target Link-layer address option was supplied, the received advertisement must update the Neighbor Cache entry as follows: - The link-layer address in the Target Link-Layer Address option must be inserted in the cache (if one is supplied and is different than the already recorded address). - IF(Solicited flag==1) { If the Solicited flag is set, the state of the entry must be set to REACHABLE. } ELSIF(Solicited flag==0 && TLLA!=LLA) { If the Solicited flag is zero and the link-layer address was updated with a different address the state must be set to STALE. } ELSE { Otherwise, the entry's state remains unchanged. } An advertisement's Solicited flag should only be set if the advertisement is a response to a Neighbor Solicitation. Because Neighbor Unreachability Detection Solicitations are sent to the cached link-layer address, receipt of a solicited advertisement indicates that the forward path is working. Receipt of an unsolicited advertisement, however, suggests that a neighbor has urgent information to announce (e.g., a changed link-layer address). If the urgent information indicates a change from what a node is currently using, the node should verify the reachability of the (new) path when it sends the next packet. There is no need to update the state for unsolicited advertisements that do not change the contents of the cache.
- The IsRouter flag in the cache entry must be set based on the Router flag in the received advertisement. In those cases where the IsRouter flag changes from TRUE to FALSE as a result of this update, the node must remove that router from the Default Router List and update the Destination Cache entries for all destinations using that neighbor as a router as specified in Section 7.3.3. This is needed to detect when a node that is used as a router stops forwarding packets due to being configured as a host. } }
================================+===============+============= NA |New State |cached LLA ---------------+-+--+-+---------+ | Destination |r| s|o|TLLA | | ===============+=+==+=+=========+===============+============= Unicast 0 0 0 none PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 0 1 none PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 1 0 none REACHABLE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 1 1 none REACHABLE unchanged ===============+=+==+=+=========+===============+============= Unicast 0 0 0 same PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 0 1 same PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 1 0 same REACHABLE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 1 1 same REACHABLE unchanged ===============+=+==+=+=========+===============+============= Unicast 0 0 0 different PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 0 1 different STALE *updated ---------------+-+--+-+---------+---------------+------------- Unicast 0 1 0 different PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Unicast 0 1 1 different REACHABLE *updated ===============+=+==+=+=========+===============+============= *Multicast 0 0 0 *none PROBE unchanged *invalid ---------------+-+--+-+---------+---------------+------------- *Multicast 0 0 1 *none PROBE unchanged *invalid ---------------+-+--+-+---------+---------------+------------- *Multicast 0 *1 0 *none PROBE unchanged *invalid ---------------+-+--+-+---------+---------------+------------- *Multicast 0 *1 1 *none PROBE unchanged *invalid ===============+=+==+=+=========+===============+============= Multicast 0 0 0 same PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Multicast 0 0 1 same PROBE unchanged ---------------+-+--+-+---------+---------------+------------- *Multicast 0 *1 0 same PROBE unchanged *invalid ---------------+-+--+-+---------+---------------+------------- *Multicast 0 *1 1 same PROBE unchanged *invalid ===============+=+==+=+=========+===============+============= Multicast 0 0 0 different PROBE unchanged ---------------+-+--+-+---------+---------------+------------- Multicast 0 0 1 different STALE *updated ---------------+-+--+-+---------+---------------+------------- *Multicast 0 *1 0 different PROBE unchanged *invalid ---------------+-+--+-+---------+---------------+------------- *Multicast 0 *1 1 different PROBE unchanged *invalid ===============+=+==+=+=========+===============+=============
N/A
The test does not invoke any remote command.
perldoc V6evalTool perldoc V6evalRemote