[SIPForum-discussion] 2 headers in one Packet?

[Bob Penfield]

If you are talking about a UDP packet, then there can only be one message per packet. RFC 3261 says this:

7.5 Framing SIP Messages

   Unlike HTTP, SIP implementations can use UDP or other unreliable
   datagram protocols.  Each such datagram carries one request or
   response.  See Section 18 on constraints on usage of unreliable
   transports.

With TCP, since it is a stream-orients protocol, you must account for the possibility of more than one message in a given IP Packet. RFC 3261 says:

   Implementations processing SIP messages over stream-oriented
   transports MUST ignore any CRLF appearing before the start-line
   [H4.1].

      The Content-Length header field value is used to locate the end of
      each SIP message in a stream.  It will always be present when SIP
      messages are sent over stream-oriented transports.
cheers,
(-:bob
________________________________
From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of John Lloyd
Sent: Friday, March 06, 2009 11:42 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] 2 headers in one Packet?

Hello All,

I've found that in certain call flow scenerio's Avaya Communication Manager is sending 2 headers in the same Packet, a 100 and also a 183.  I've looked through the SIP RFC but can't find any information on this.

This isn't breaking the call flow, but I'm curious if the UAS is violating RFC 3261.

Thanks,
John


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