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Re: [Sip] a question on section 18.2.2 in RFC 3261



The reason was simple - pretty much all protocols where you send a request on TCP expect a response on TCP under normal conditions (normal being, the connection still exists). Anything else is going to be more complicated for no gain.

-Jonathan R.

Ryan Kereliuk wrote:
On Tue, May 27, 2003 at 11:27:28AM -0600, Wang, Jin-Gen wrote:

Since the Via header has enough information (IP address + port +
transport protocol) for an application to send back response messages,
what is the design idea behind the above decision to request an
application to send back responses using an existing connection if the
connection is still open, other than (may be) optimization in
implementation? In other words, from SIP protocol point of view, why is
such request a MUST requirement?

There are a variety of reasons why this is good including traversal of
of NAT/PAT devices.  I think the motivation for the text as written,
however, was to head off potential scaling and performance problems
associated with doubling the number of TCP/SCTP/TLS connections in use.

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Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
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_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors@cs.columbia.edu for questions on current sip
Use sipping@ietf.org for new developments on the application of sip