[SIPForum-discussion] Sequence of Via headers

[Stephen James]

Entirely valid - not recommended because Via is essential to processing. For a UAS, the top Via is encountered first for validation.


 
Stephen James 
sjames_1958 at yahoo.com
 
We are not princes of the earth, we are the descendants of worms, and any nobility must be earned.



________________________________
 From: Abhishek Gupta <gupta.kumar.abhishek at gmail.com>
To: "discussion at sipforum.org" <discussion at sipforum.org> 
Sent: Friday, July 5, 2013 6:52 AM
Subject: [SIPForum-discussion] Sequence of Via headers
 


Hi,

This is related to the sequence of Via headers. We all know that it is copied from the request in the same order while forming the response and sent to the topmost Via order. How valid is the below mentioned 180 response (having Via headers at different places) -

INVITE sip:1002 at 10.44.104.117:5060;transport=udp SIP/2.0
Record-Route: <sip:10.44.104.156;lr=on>
Via: SIP/2.0/UDP 10.44.104.156;branch=z9hG4bK7805.472b72f2.0
Via: SIP/2.0/UDP 10.44.104.119:32986;branch=z9hG4bK-d8754z-fdbc5e3d0e2c5a3d-1---d8754z-;rport=32986
Max-Forwards: 16
Contact: <sip:1001 at 10.44.104.119:32986;transport=udp>
.
.
Content-Length: 216


SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 10.44.104.156;branch=z9hG4bK7805.472b72f2.0
From: "1001"<sip:1001 at 10.44.104.156>;tag=87b60828
To: <sip:1002 at 10.44.104.156>;tag=331752176
Contact: <sip:1002 at 10.44.104.117:5060;transport=udp>
Call-ID: NTY3ZmQyZDgzM2JiMjQ5MjI3MDZjZDc5MDFiMjBjZmY
CSeq: 1 INVITE
Content-Length: 0
Via: SIP/2.0/UDP 10.44.104.119:32986;rport=32986;branch=z9hG4bK-d8754z-fdbc5e3d0e2c5a3d-1---d8754z-
Record-Route: <sip:10.44.104.156;lr=on>
Allow: ACK, BYE, CANCEL, INVITE, MESSAGE, NOTIFY, OPTIONS, PRACK, REFER, UPDATE


Regards,
Abhishek
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