[Serusers] Another Looping Question

Fri Apr 15 20:16:26 CEST 2005

Paul,

Sorry it this was unclear.  I meant to say that I don't think UA should
respond with ACK to provisional response (i.e. 100 Trying). I just scanned
through an RFC and did not see anywhere where it says provisional responses
should be ACKed. Also, I am unclear on why UA changed CSEQ. Any ideas on
that?

Alex

  _____  

From: Java Rockx [mailto:javarockx at gmail.com] 
Sent: Friday, April 15, 2005 2:12 PM
To: Alex Vishnev
Cc: serusers at lists.iptel.org
Subject: Re: [Serusers] Another Looping Question

Thanks Alex.

So just to be clear, are you saying this:

1) When ser receives an INVITE it does not need to reply with "100 Trying"

2) When the SER tm module sends back the 100 Trying, the SIP UA should not
be changing the Cseq header?

Regards,
Paul
On 4/15/05, Alex Vishnev <avishnev at optonline.net> wrote:
Paul,

It looks like UA ACK 100 Trying. First of all I don't believe this is
needed. Second of all, it changes CSEQ from 101 INVITE to 100. I think
that's not valid at all. 
HTH

Alex

  _____  

From: serusers-bounces at lists.iptel.org [mailto:
<mailto:serusers-bounces at iptel.org>  serusers-bounces at lists.iptel.org] On Behalf
Of Java Rockx
Sent: Friday, April 15, 2005 10:46 AM
To: serusers at lists.iptel.org
Subject: [Serusers] Another Looping Question

Hi All.

Below is a snippet of an INVITE and you can see the usual "trying - your
call is important to us" in the dialog. Anyhow, for some reason SER
occasionally attempts to sent the ACK to itself, which causes a looping
condition. The last ACK shown is the start of the looping condition.

It only happens on occasion. SER should have consumed the ACK rather than
attempted to forward it.

Can anyone explain this?

Regards,
Paul

IP Legend
-------------------
10.3.0.221 - SER (behind a Cisco 3600 so ALG rewrote the IPs)
69.36.46.178 - NATed SIP UA

U 2005/04/15 02:19:16.252614 69.35.46.178:5060 -> 10.3.0.221:5060
INVITE sip:8187768080 at sipdev.mycompany.net SIP/2.0.
Via: SIP/2.0/UDP 192.168.1.102:5060;branch=z9hG4bK3915905414.
From: Test User <sip:3215591439 at sipdev.mycompany.net>;tag=1465261089.
To: <sip:8187768080 at sipdev.mycompany.net>.
Call-ID: 2671219156 at 192.168.1.102.
CSeq: 101 INVITE.
Contact: <sip:3215591439 at 192.168.1.102:5060>.
Proxy-Authorization: Digest username="3215591439",
realm="sipdev.mycompany.net",
nonce="425f5e0de25efdb3f5a6125dcf2147bf30fe9177",
uri="sip:8187768080 at sipdev.mycompany.net ",
response="61996c3bdc10990fec7e245751777516", algorithm=MD5,
cnonce="ae02e47a3355bada49ce344c92f48587", qop=auth, nc=00000002.
max-forwards: 70.
Allow: INVITE, ACK, CANCEL, BYE, REFER, NOTIFY.
Content-Type: application/sdp.
Content-Length:   180.
.
v=0.
o=- 32014 3005 IN IP4 192.168.1.102.
s=-.
c=IN IP4 192.168.1.102.
t=0 0.
m=audio 13456 RTP/AVP 18 0 8 2 4 101.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=ptime:20.
.

#
U 2005/04/15 02:19:16.276216 10.3.0.221:5060 -> 69.35.46.178:5060
SIP/2.0 100 trying -- your call is important to us.
Via: SIP/2.0/UDP
192.168.1.102:5060;branch=z9hG4bK3915905414;rport=5060;received=
69.35.46.178 <http://69.35.46.178> .
From: Test User <sip:3215591439 at sipdev.mycompany.net>;tag=1465261089.
To: <sip:8187768080 at sipdev.myvox.net>.
Call-ID: 2671219156 at 192.168.1.102.
CSeq: 101 INVITE.
Content-Length: 0.
.

#
U 2005/04/15 02:19:16.792795 69.35.46.178:5060 -> 10.3.0.221:5060
ACK sip:8187768080 at sipdev.mycompany.net SIP/2.0.
Via: SIP/2.0/UDP 192.168.1.102:5060;branch=z9hG4bK3499714875.
From: Test User <sip:3215591439 at sipdev.mycompany.net>;tag=1465261089.
To:
<sip:8187768080 at sipdev.mycompany.net>;tag=cdbfe46960d7566fcbe09f199f2b328d.c
2bb.
Call-ID: 2671219156 at 192.168.1.102.
CSeq: 100 ACK.
Content-Length: 0.
.

#
U 2005/04/15 02:19:16.912146 10.3.0.221:5060 -> 10.3.0.221:5060
ACK sip:8187768080 at sipdev.mycompany.net SIP/2.0.
Max-Forwards: 10.
Record-Route: <sip:10.3.0.221;ftag=1465261089;lr>.
Via: SIP/2.0/UDP 10.3.0.221;branch=0.
Via: SIP/2.0/UDP 192.168.1.102:5060;received= 69.35.46.178
<http://69.35.46.178> ;branch=z9hG4bK3499714875.
From: Test User <sip:3215591439 at sipdev.mycompany.net>;tag=1465261089.
To:
<sip:8187768080 at sipdev.mycompany.net>;tag=cdbfe46960d7566fcbe09f199f2b328d.c
2bb.
Call-ID: 2671219156 at 192.168.1.102.
CSeq: 100 ACK.
Content-Length: 0.
P-hint: Local Destination.

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