I really did mean to talk about unicast as opposed to any kind of anycast, because the most recent published description of a scheme for using well-known addresses to access DNS service <draft-ietf-ipv6-dns-discovery-07.txt> specifies unicast. If I remember correctly, the earlier discussion about well-known addresses progressed from specifying anycast to unicast because of concerns that "just propagate host routes to those service addresses in the internal routing" might prove to be complicated in practice.
- Ralph
At 03:54 PM 8/7/2003 +0300, Pekka Savola wrote:
On Thu, 7 Aug 2003, Ralph Droms wrote: > I believe there is also a scaling issue. If the well-known address > mechanism is truly limited to unicast (and not anycast) addressing, an > enterprise can only deploy as many recursive name servers as there are > reserved, well-known addresses.
It depends on what you mean by "anycast" here.
If well-known addresses are shared-unicast addresses (by the terminology of draft-ietf-ipngwg-ipv6-anycast-analysis-02.txt), it might go easier.
You could just deploy the same (service) address in a lot of different nodes, and just propagate host routes to those service addresses in the internal routing; so, there could be more servers, but based on one node's temporal view of the topology, it could only see N (e.g. three) at the time and the place.
> Another potential issue is that deployment of hosts using the well-known > addresses will force network operators to support DNS service at those > well-known addresses, even if some other service architecture would be > better suited to that network's requirements.
Agreed, this may be an issue. However, just as well you could redirect all of those to a box (even a router) which could proxy those requests to some otherwise configured DNS servers.
-- Pekka Savola "You each name yourselves king, yet the Netcore Oy kingdom bleeds." Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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