On Tue, 11 Jul 2006, Julien Laganier wrote:
==> I think you should go a bit deeper on this. Important question
to ask should be, "What impact does enabling this mechanism at one
end have, when it isn't supported on the other?" For example, in
HIP there are extra DNS requests for new RR with HIP, with fallback
to A/AAAA (i.e., extra delay of at least 1 DNS roundtrip, possibly
more when trying to connect to any non-HIP destination).
I don't think that is necessarily the case. The HIP DNS draft has no
normative text describing that lookups should be serialized and
ordered. It is entirely possible that you issue simultaneously A/AAAA
and HIP RR QUERIES (and I was told my DNSext people that it's not a
problem.) If you receive a HIP RR the other end does support HIP and
you establish an association, and if no HIP RR comes back you connect
with plain IP.
I've certainly advocated this approach myself for AAAA/A lookup
problems (RFC 4472, section 5.1). I'm not sure whether or how widely
parallel lookups have been implemented. I've heard some comments of
application complexity of handling asynchronous events and/or
threading with various possible results, but it's unclear whether this
would be a real impediment. Certainly, I'd be interested in any
implementation experience in this area.
--
Pekka Savola "You each name yourselves king, yet the
Netcore Oy kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
_______________________________________________
Int-area mailing list
[email protected]
https://www1.ietf.org/mailman/listinfo/int-area
