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2 Replies Last post: Jan 6, 2010 11:26 PM by joegen  
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austincao
16 posts since
Nov 11, 2009

Jan 6, 2010 2:56 AM

opensbc remove some parameters in Via header?


Hi all,


Recently I did a test with Sailfin, I found that "belb" (back-end load balance) parameter in
Via was removed by OpenSBC, and that maybe cause Sailfin just drop the
subsequent responses.
Actually, I could see the "belb" parameter in Via header from the packet captured by Wireshark, while from the OSBC log, I could NOT find any "belb" in Via.

I didn't dig the source code to find how OpenSBC parse the SIP message and process the Via headers. So I want ask if anyone has encounter this problem?

I hope that someone could give me some tips.Thank you!
Brs,
austincao

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austincao
16 posts since
Nov 11, 2009
1. Jan 6, 2010 3:20 AM in response to: austincao
Re: opensbc remove some parameters in Via header?
I also find another issue:
Let's see the following SIP header,

it is the contact header of the Register that will be sent by OpenSBC to the Upper Reigstrar:

Contact:　sip:x-reg-id-sip%3A10%40*172.19.1.109*%3A5060%3Bsend-addr%3D172.19.1.159%3A5060@172.16.0.164:5062

while 172.19.1.109 is the IP address of the client;

172.19.1.159 is the IP address of Openser, which act as the load balancer;

and 172.16.0.164 is the internal IP address of OpenSBC that connect to the SIP server.

We checked out the latest OpenSBC to support dual NICs

We could find that "%3B" stands for ";" in some field. However, it seems that what OpenSBC can process is just ";".

When we INVITE sip:x-reg-id-sip%3A10%40172.19.1.109%3A5060%3Bsend-addr%3D172.19.1.159%3A5060@172.16.0.164:5062,

OpenSBC will send the INVITE message to 172.19.1.159;

while if we INVITE sip:x-reg-id-sip%3A10%40172.19.1.109%3A5060;_send-addr%3D172.19.1.159%3A5060@172.16.0.164:5062,

OpenSBC will send the INVITE message to 172.19.1.109, which is exactly right.

So,I don't knw why.

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joegen
519 posts since
Apr 28, 2007
2. Jan 6, 2010 11:26 PM in response to: austincao
Re: opensbc remove some parameters in Via header?

Yes that is the intended call flow. All request towards your UA must pass through SER. Most NAT will drop packets if it comes from an entity that it has no previous connection with.

The INVITE that SER will receive from OpenSBC would look like this

INVITE sip:10@172.19.1.109:5060 SIP/2.0

If your SER (172.19.1.159) is unable to route this perfectly formed request URI to its intended target, then that is a routing issue in SER and not OpenSBC.


Joegen

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