[Serusers] Via tags question...

Jiri Kuthan jiri at iptel.org
Thu Feb 20 17:19:21 CET 2003


Greg,

via stack must be returned in replies from upstream as sent there in requests
(8.2.6.2 in 3261). Perhaps with some additional parameters on topmost via 
(recevied, rport) but definitly without any deletions. So the example you 
sent us is broken due to the server. If it was at least the topmost via 
which was broken, but breaking a via lower in the via-stack is really surprising. 
The UAA is probably confused by whitepace in the second via, which is however correct:

via->params =...*(SEMI via_params)
SEMI=SWS ";" SWS
SWS=[LWS] ([] hint that parameter optional)

that's what I think. 

>U 2003/02/19 18:36:20.276844 164.9.42.25:5060 -> 184.294.324.2:5060
>INVITE sip:12143357976 at 184.294.324.2:5060 SIP/2.0.
>Via: SIP/2.0/UDP 164.9.42.25;branch=z9hG4bKcc26.d3c125d.0.
>Via: SIP/2.0/UDP 216.87.145.22:4060 ;branch=z9hG4bK-3e542304-23dfc-ea2.

>U 2003/02/19 18:36:20.902858 184.294.324.2:5060 -> 164.9.42.25:5060
>SIP/2.0 100 Trying .
>Via: SIP/2.0/UDP 164.9.42.25;branch=z9hG4bKcc26.d3c125d.0.
>Via: SIP/2.0/UDP 216.87.145.22:4060.

-jiri

ps -- a callflow generation tool I'm aware of is
http://sourceforge.net/projects/callflow/
-- but I never gave it a try. (If I recall right, it takes a Java tool which
I don't have on my computer.)

At 04:25 PM 2/20/2003, Greg Fausak wrote:
>This is a protocol question, I don't know if it is directly related
>to ser.  Concerning the Via tags, should any proxy/gateway modify tags
>that don't belong to it, or should they simply be copied verbatum?
>
>For example, I have a situation where I send an INVITE message, and the
>TRYING response I receive modifies one of the Via: tags.  I don't think
>this is right.  Here are the two packets in question:
>
>#
>U 2003/02/19 18:36:20.276844 164.9.42.25:5060 -> 184.294.324.2:5060
>INVITE sip:12143357976 at 184.294.324.2:5060 SIP/2.0.
>Max-Forwards: 10.
>Record-Route: <sip:12143357976 at 164.9.42.25;branch=0>.
>From: <sip:8178863582 at 216.87.145.22> ;tag=d8579116-fdc-3e542303-23d34-4a84.
>To: <sip:12143357976 at augustvoice.net> ;user=phone.
>Call-ID: 59fd88-d8579116-fdc-3e542303-23d2f-3897 at 216.87.145.22.
>CSeq: 2 INVITE.
>Via: SIP/2.0/UDP 164.9.42.25;branch=z9hG4bKcc26.d3c125d.0.
>Via: SIP/2.0/UDP 216.87.145.22:4060 ;branch=z9hG4bK-3e542304-23dfc-ea2.
>Contact: <sip:8178863582 at 216.87.145.22:4060>.
>User-Agent: FXS_GW (sip1028a.bin).
>Content-Type: application/SDP.
>Content-Length:291.
>P-hint: LD GATEWAY.
>.
>v=0.
>o=FXS_GW 12367 0 IN IP4 216.87.145.22.
>s=Audio Session.
>i=Audio Session.
>c=IN IP4 216.87.145.22.
>t=0 0.
>m=audio 16384 RTP/AVP 0 18 4 8 96.
>a=fmtp:96 0-11.
>a=rtpmap:0 PCMU/8000/1.
>a=rtpmap:18 G729/8000/1.
>a=rtpmap:4 G723/8000/1.
>a=rtpmap:8 PCMA/8000/1.
>a=rtpmap:96 telephone-event/8000.
>
>
>And your response is:
>#
>U 2003/02/19 18:36:20.902858 184.294.324.2:5060 -> 164.9.42.25:5060
>SIP/2.0 100 Trying .
>Via: SIP/2.0/UDP 164.9.42.25;branch=z9hG4bKcc26.d3c125d.0.
>Via: SIP/2.0/UDP 216.87.145.22:4060.
>From: <sip:8178863582 at 216.87.145.22> ;tag=d8579116-fdc-3e542303-23d34-4a84.
>To: <sip:12143357976 at augustvoice.net> ;user=phone;tag=27DC1DCC-F61.
>Date: Thu, 20 Feb 2003 00:36:20 GMT.
>Call-ID: 59fd88-d8579116-fdc-3e542303-23d2f-3897 at 216.87.145.22.
>Server: Cisco-SIPGateway/IOS-12.x.
>CSeq: 2 INVITE.
>Allow-Events: telephone-event.
>Content-Length: 0.
>.
>
>See how the :
>        Via: SIP/2.0/UDP 216.87.145.22:4060 ;branch=z9hG4bK-3e542304-23dfc-ea2.
>Has been changed to:
>        Via: SIP/2.0/UDP 216.87.145.22:4060.
>
>
>Does anyone have any perl script to take a ngrep protocol dump
>and print it out in a pretty way?
>
>---greg
>Greg Fausak
>August.Net Services, LLC
>
>
>
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--
Jiri Kuthan            http://iptel.org/~jiri/ 




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