Question on address configuration

[Matthew Lehman]

> -----Original Message-----
> From: Pekka Savola [mailto:pekkas@netcore.fi]
> Sent: Wednesday, January 09, 2002 11:15 AM
> To: Matthew Lehman
> Cc: 6BONE List; Edward Lewis
> Subject: RE: Question on address configuration
> 
> On Wed, 9 Jan 2002, Matthew Lehman wrote:
> > What about a well-known anycast address for the DNS server to listen
on.
> > The clients could use the well-known address and would only require
> > configuration once, it's reasonably scalable (just add more DNS
servers
> > listening on the address), and it does not require any special
changes
>
^^^^^^^^^^^^^^^^^^^
> > to any protocols.
>   ^^^^^^^^^^^^^^^^
> 
> Are you sure about this?  This is different from IPv4 "anycast".  IPv6
> anycast address cannot be used as a source address.  Therefore,
according
> to e.g.:
> 
> draft-ietf-ipngwg-ipv6-anycast-analysis-00.txt
> 
> many DNS implementations may check the source address of the replies
to
> the queries; thus use of anycast in this scenario might require
> protocol/implementation changes.

I agree.  I just don't think getting the server or resolver to be
anycast aware requires an rfc or new protocol.  I do think there would
need to be some implementations changes as I don't believe there is a
way to make this work currently.  I could be easily be wrong.

> > It does require anycast listening support and I don't
> > know of any platforms that currently have it.  Someone on the list
might
> > know more about implementations in the works.
> 
> Anycast Listening is not a problem, e.g. KAME/BSD have had it for a
long
> time now, USAGI for Linux just got it.
> 
> FWIW, I've used IPv6 anycast address for about half a year in a 6to4
relay
> setup.
>
> --
> Pekka Savola                 "Tell me of difficulties surmounted,
> Netcore Oy                   not those you stumble over and fall"
> Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords