On Mon, 04 Jul 2011 21:01:27 +1000 Karl Auer <ka...@biplane.com.au> wrote:
> On Mon, 2011-07-04 at 17:23 +0930, Mark Smith wrote: > > The reserving of addresses is so that the are autoconfigured and > > therefore well known and "well available" ones. It's no different to the > > idea of having reserved well known ports, multicast groups or unicast > > addresses. > > That's fine - but we should not reserve addresses unless there is a > point to doing so. > I can see no reason why there should be a group of > addresses designated "anycast" at the top of the subnet (the subnet > anycast addresses). And so far, no-one has provided a use case that > shows why they need to be reserved. > Sometimes you have to have the base capability widely available before it is attractive to people to use. By insisting on a use case, you may be creating a chicken and egg problem. See the "success" of IPv4 multicast, bearing in mind that it was specified in RFC1119, August 1989. Perhaps it would have been more widely used if it had been more widely available in the 90s. That's why it's been part of IPv6 from day one. If every router supports the subnet anycast address, because it is a mandated requirement, you can develop and deploy something that relies on it. If the availability is limited, you end up duplicating the same mechanism some other way at the cost of additional effort, or don't bother at all because those additional costs are too high. > > Yes, there is (and has to be) a flag specified when the address is > > assigned to nominate it as an anycast address. > > I'm glad there is, because that means we do not need to reserve those > addresses. > > Regards, K. > > -- > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Karl Auer (ka...@biplane.com.au) +61-2-64957160 (h) > http://www.biplane.com.au/kauer/ +61-428-957160 (mob) > > GPG fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687 > Old fingerprint: B386 7819 B227 2961 8301 C5A9 2EBC 754B CD97 0156 -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
