[SR-Users] Question on ACK behavior

[Daniel-Constantin Mierla]

Hello,

On 8/3/12 1:43 AM, Varsha Venkatraramani wrote:
>
>     I have a question regarding the below ACK response Kamilaio
>     receives from a carrier.Can  someone please help me understand why
>     the "*Route: sip:callmanager at 192.168.160.43:5060> *sent from
>     Kamailio is missing a "<" as shown in the captures below? Our
>     Internal proxy is treating that as a malformed header and dropping
>     the packet.
>
>     *ACK from CARRIER*
>
>     U 2012/08/01 18:32:52.219852 4.55.18.227:5060
>     <http://4.55.18.227:5060> -> 192.168.160.47:5060
>     <http://192.168.160.47:5060>
>
>     *ACK sip:callmanager at 192.168.160.43:5060 SIP/2.0.*
>
>     Via: SIP/2.0/UDP 4.55.18.227:5060;branch=z9hG4bK04B0eef33040e9b8e70.
>
>     From: sip:+14088442721 at 4.55.18.227:5060;tag=gK043001e3.
>
>     To: sip:+19728931740 at 192.168.160.47:5060;tag=b307370c678f3b44.
>
>     Call-ID: 295226_50030734 at 4.55.18.227
>     <mailto:295226_50030734 at 4.55.18.227>.
>
>     CSeq: 18079 ACK.
>
>     Max-Forwards: 70.
>
>     Route: <sip:192.168.160.47:5060;lr=on>.
>
>     *Route: <sip:2c6c6d1ab58c623912f6b8a6ee526982 at 192.168.160.44:5060>.*
>
>     Content-Length: 0.
>
>     .
>
>     *ACK FORWARDED TO SIP PROXY*
>
>     U 2012/08/01 18:32:52.220612 192.168.160.47:5060
>     <http://192.168.160.47:5060> -> 192.168.160.44:5060
>     <http://192.168.160.44:5060>
>
>     *ACK sip:2c6c6d1ab58c623912f6b8a6ee526982 at 192.168.160.44:5060
>     SIP/2.0.*
>
>     Via: SIP/2.0/UDP 192.168.160.47;branch=z9hG4bKcydzigwkX.
>
>     Via: SIP/2.0/UDP 4.55.18.227:5060;branch=z9hG4bK04B0eef33040e9b8e70.
>
>     From: sip:+14088442721 at 4.55.18.227:5060;tag=gK043001e3.
>
>     To: sip:+19728931740 at 192.168.160.47:5060;tag=b307370c678f3b44.
>
>     Call-ID: 295226_50030734 at 4.55.18.227
>     <mailto:295226_50030734 at 4.55.18.227>.
>
>     CSeq: 18079 ACK.
>
>     Max-Forwards: 69.
>
>     Content-Length: 0.
>
>     *Route: sip:callmanager at 192.168.160.43:5060>.*
>
>     I have attached the config file for you reference. Kamailio
>     version is 3.2.3
>
the next proxy does strict routing, because the Route header has not 
'lr' parameter. Based on SIP specs, Kamailio has to take that route and 
set it as r-uri and the r-uri has to be added as last route, so next 
proxy will be able to do forwarding based on strict routing rules. Maybe 
there is an option in that device at 192.168.160.44 to do loose routing, 
which is the recommended one in RFC3261 (strict routing is from the old 
rfc of SIP).

Regarding the missing '<' in the Route header sent out from Kamailio, 
there was an issue in the code handling this specific situation, should 
be fixed now by commit:
http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=cbb62f8619b513605498d00abc5d4c8b2f5654d7

You have to apply that patch or use the latest git branch 3.2. Let us 
know if works fine.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 - http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 - http://asipto.com/u/kpw

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sip-router.org/pipermail/sr-users/attachments/20120803/493e3bbf/attachment.htm>