Subject: RE: rfc2461bis issue 257 resolved? fast RA issue

From: "Soohong Daniel [email-masked]" <[email-masked]>
Date: Wed, 01 Jun 2005 08:53:17 +0900

for folks information.

> draft-pettland already contains something to 
> speed up the RA. It doesn't have to be a 
> separate WG item.

Agreed.

http://www.watersprings.org/pub/id/draft-pentland-dna-protocol-00.txt

3.3  Fast Router Advertisment

   According to RFC 2461 a solicited Router Advertisement should have a
   random delay between 0 and 500 milliseconds, to avoid the
   advertisements from all the routers colliding on the link causing
   congestion and higher probability of packet loss.  In addition, RFC
   2461 suggests that the RAs be multicast, and multicast RAs are rate
   limited to one message every 3 seconds.  This implies that the
   response to a RS might be delayed up to 3.5 seconds.

   DNAv6 avoids this delay by using a different mechanism to ensure that
   two routers will not respond at exactly the same time while allowing
   one of the routers on the link to respond immediately.  Since the
   hosts might be likely to use the first responding router as the first
   choice from their default router list, the mechanism also ensures
   that the same router doesn't respond first to the RSs from different
   hosts.

   The mechanism is based on the routers on the link determining (from
   the same RAs that are used in section Section 3.1 to determine all
   the prefixes assigned to the link), the link-local addresses of all
   the other routers on the link.  With this loosely consistent list,
   each router can independently compute some function of the (link-
   local) source address of the RS and each of the routers' link-local
   addresses.  The results of that function are then compared to create
   a ranking, and the ranking determines the delay each router will use
   when responding to the RS.  The router which is ranked as #0 will
   respond with a zero delay.

   If the routers become out-of-sync with respect to their learned
   router lists, two or more routers may respond with the same delay,
   but over time the routers will converge on their lists of learned
   routers on the link.

---------------------------------------------
Daniel (Soohong Daniel Park)
Mobile Platform Laboratory, SAMSUNG Electronics.

--------------------------------------------------------------------
IETF IPv6 working group mailing list
[email-masked]
Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6
--------------------------------------------------------------------