Re: Anycast support in draft-ietf-ipv6-addr-arch-v4-02.txt

[Joe Abley <jabley at isc.org>]

On 13 Apr 2005, at 21:06, Rob Austein wrote:

> So the criteria here are:
>
> a) Short-lived session (typically two packet UDP exchange, but some
>    argue that even a fast 7 packet TCP exchange is ok, so long as it's
>    fast);

For the record, I know of people who have distributed video streaming 
services and ftp servers using anycast, with attendant long-held, 
million-packet TCP sessions, and who have done so very successfully. 
POP3 and SMTP services have been anycast in real, live ISPs' production 
networks for a long time (I know of an example that dates back at least 
10 years).

As I noted in my reply to Bob, the nature of the protocol is not the 
final discriminator here -- it's the protocol *and* the network *and* 
the distribution of nodes, and a comprehensive treatment (such as might 
be expected if MUST NOTs are showing up in the text) is not going to 
fit in this draft.

> > Another approach is to write a separate document that relaxes the 
> > rules and
> > describes the issues in more depth than we might want to add here.  
> > This
> > would keep the current limits in the address architecture (going 
> > forward to
> > Draft standard) and have the new document start at Proposed standard.

Such a draft already exists in the form of 
draft-jabley-v6-anycast-clarify, which tersely defers most commentary 
to the grow draft. If there is a use for that draft, then perhaps it 
lies in being able to include a normative reference to the grow draft 
without holding the v6 architecture document too long in the RFC 
editor's queue (waiting for the grow document to be WGLCd and 
published).

> [...] Anycast is mostly an IP issue, not an IPv6 or IPv4 issue.

That is my view, too, which is why I keep trying to illustrate this v6 
discussion with examples of v4 anycast deployment.


Joe


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