>
> >> there was a question regarding to DNS response against this kind of
> >> query:
> >> (src=x dst=anycast)
> >> needs to have anycast source address or not.
> > I would be setting the anycast address as the source address of the
> > reply.
>
> under limitation declared in RFC2373, we cannot.
Well this is all moot as anycast addresses are not allowed to
be assigned to hosts and DNS service is host functionality.
"There is little experience with widespread, arbitrary use of internet
anycast addresses, and some known complications and hazards when
using them in their full generality [ANYCST]. Until more experience
has been gained and solutions agreed upon for those problems, the
following restrictions are imposed on IPv6 anycast addresses:
o An anycast address must not be used as the source address of an
IPv6 packet.
o An anycast address must not be assigned to an IPv6 host, that
is, it may be assigned to an IPv6 router only."
In the IPv4 world we are expecting the source address of
the DNS reply to match the destination address in the
anycast case.
The restiction on source address is primarily driven by
TCP and load balancing causing multiple anycast hosts to
receive one TCP stream.
Also how do you get experience that would break the above
restiction without breaking the above restiction. Classic
catch 22.
To get around the truncation and tcp fallback we could have
a EDNS option that specified a unicast address to use that
is sent back with the truncated response. Or do we just send
this EDNS response and force a switch to unicast regardless of
TC.
Mark
--
Mark Andrews, Nominum Inc.
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: [EMAIL PROTECTED]
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