[Serusers] Via tags question...

Greg Fausak lgfausak at august.net
Thu Feb 20 16:25:13 CET 2003


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






More information about the sr-users mailing list