Hi Karl, On Mon, 04 Jul 2011 14:23:47 +1000 Karl Auer <ka...@biplane.com.au> wrote:
> On Mon, 2011-07-04 at 13:28 +0930, Mark Smith wrote: > > Perhaps we should wait until IPv6 traffic exceeds IPv4's before > > deciding. With the trivial amount of use that IPv6 currently has, it > > makes no sense to say history shows it hasn't been useful and should be > > deprecated. > <snip> I missed this earlier - > Note that the subnet router anycast address doesn't > even ensure that the "nearest" router is contacted, which would arguably > have been useful, because the current spec deliberately builds in a > small random delay in responding, to avoid network congestion. > Are you referring to rfc4861, section 7.2.7? The thing that makes the first/quickest response "stick" is the Override flag being set to 0 - " Second, the Override flag in Neighbor Advertisements SHOULD be set to 0, so that when multiple advertisements are received, the first received advertisement is used rather than the most recently received advertisement." So the difference between IPv4 ARP and IPv6 ND is that IPv4 ARP will always use the most recent/last reply it received. Normal unicast IPv6 ND works the same way, for NAs that have the default of the Override flag set. When a NA for an anycast address is sent/received, the Override flag is not set, and therefore the receiving host will use the information in the first and quickest response it received rather than the last. I don't seem to be able to find anything that says subnet router anycast addresses are to be treated differently to the above, have you a reference I could look at? Thanks, Mark. -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
