NAME

hostRecvRaNHD - Verifying net-hop determination

TARGET

Host only

SYNOPSIS

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

INITIALIZATION

1. Clear the Prefix List that was learned by RAs.
2. Clear the Default Router List.
3. Set its state to REACHABLE.
4. The Router Lifetime of a RA is ether 0 or 600.
5. A RA includes or excludes a prefix option.

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


  State: NONCE (for TN)


  ==== unsolicited RA ===>
       src=TN's link-local
       dst=all-node
       M=0, O=0
       RouterLifetime=0 or 600
       ReachableTime=0
       RetransTimer=0
       w/ SLLA
       w/o Prefix option or Prefix Option:
           L=1, A=1
           ValidLifetime=2592000
           PreferredLifetime=604800
           Prefix=3ffe:501:ffff:100::/64


  State: STALE (for TN)


  <=== Ns for DAD (if any) ====
       src=unspecified
       dst=solicited-node[NUT's global, prefix=3ffe:501:ffff:100::/64]
       target=NUT's global


  Wait (3 sec)


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


  State: REACHABLE (for TN)

TEST PROCEDURE

• A case where a given address should be off-link
• A cast where a given address should be on-link

Off-link

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


  State: REACHABLE (for TN)


  ==== echo-request ===>
       src=off-link global, but LLA is TN's one
       dst=NUT's global


  <=== Judgement #2: echo-reply ====
       src=NUT's global
       dst=off-link global, but LLA is TN's one






On-link
  TN               NUT
  ----------------------


  State: REACHABLE (for TN)


  ==== echo-request ===>
       src=off-link global, but LLA is TN's one
       dst=NUT's global


  <=== Judgment #3: multicast NS ====
        src=NUT's link-local
        dst=solicited-node[off-link global]
        target=off-link global
        w/ SLLA




JUDGMENT
1. Next-hop determination


5.2.  Conceptual Sending Algorithm


     Next-hop determination for a given unicast destination operates as
     follows.  NUT performs a longest prefix match against the
     Prefix List to determine whether the packet's destination is on- or
     off-link.  If the destination is on-link, the next-hop address is the
     same as the packet's destination address.  Otherwise, NUT
     selects a router from the Default Router List.  If the Default Router
     List is empty, NUT assumes that the destination is on-link.

  =========+========+==========================================
  RA recieved       | NUT
  by NUT            |
  ---------+--------+-----------------+-------------+---------
  Prefix   |Router  | The Prefix List | The Default | Next Hop
  Option   |Lifetime|                 | Router List |
  =========+========+=================+=============+==========
  none     | 0      | empty           | empty       | on-link
  ---------+--------+-----------------+-------------+----------
  none     | 600    | empty           | NOT empty   | off-link
  ---------+--------+-----------------+-------------+----------
  exist    | 0      | NOT empty       | empty       | on-link
  =========+========+=================+=============+==========



  2. NUT throws an echo-reply to the default router (i.e. TN)
     because the given address should be off-link.



  3. NUT sends multicast NSs for the given address
     because it should be on-link.




TERMINATION

  Send RA with RouterLifetime=0 to clear the Default Router List.


  Clear the Prefix List and the Defaut Router List by remote commands. XXX



NOTE



  1. RFC2461 describes that a host assumes the destination is on-link
     if the Default Router List is empty. However, it also describes
     that multihomed related issues are not concerned.
     It is also one of the issues that a host assumes an address is
     on-link if the Default Router List is empty. This test judges
     NUT "WARN" instead of "FAIL" in such case.




  2. The echo request that NUT captures has an off-link source address
     and a link-local soruce address. It is reasonable for NUT not to
     throw the echo-reply to the default router because its source
     address is a link-local. This test judges NUT "WARN" insted of "FAIL"
     in such case.


  3. The test invokes the following command:
     - Clear the Prefix List
     - Clear the Default Router List



SEE ALSO

  perldoc V6evalTool
  perldoc V6evalRemote