Re: [Sip] WGLC: draft-ietf-sip-connect-reuse-08.txt

Paul Kyzivat wrote:
> I think much less should be said.
> 
> Don't say that A must reject requests sent to it over the connection. 
> But also don't specify, or even imply, a mechanism by which B might 
> decide it is ok to send requests on this connection.

Any way you cut, slice, and dice this thing, TCP connection reuse
in the backwards direction is bad.  Note that it does not work with
virtual servers at all.

Unfortunately, people are using it and as such something ought to
be said about it in the draft.  I agree that as the less said, the
better.  I also agree that putting the "alias" parameter in the
Via request for TCP.

Going back to our scenario of A opening a connection to B, it
probably suffices to massage the text you proposed in an earlier
email of this thread:

    B MUST NOT reuse this connection for requests to the
    supposed party at the other end UNLESS it has some way
    of verifying the identity of that party to the same level
    of assurance as it would have by doing the DNS lookup and
    establishing its own connection. For instance, if a DNS
    lookup resolved to the same address and port as the source
    port of the inbound connection then that ought be be good
    enough.

This still does not solve the problem of reusing TCP connections
for virtual servers; i.e., B does not know that that A's physical
IP address is being used by multiple virtual domains.  Again, I
can just point this out for the TCP and SCTP transport in
the virtual server section more emphatically and leave it at that.

- vijay
-- 
Vijay K. Gurbani, Bell Laboratories, Alcatel-Lucent
2701 Lucent Lane, Rm. 9F-546, Lisle, Illinois 60532 (USA)
Email: vkg@{alcatel-lucent.com,bell-labs.com,acm.org}
WWW:   http://www.alcatel-lucent.com/bell-labs

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