[Serusers] SER generating Via: with branch parameter equal to "0" over half the time

[Michal Matyska]

Use syn_branch=0 in your ser.cfg. This will put RFC compliant branch ids
into positive ACKs in exchange of few CPU cycles wated to calculate the
id instead of using tm transaction id :-)

Michal

Frank Durda IV píše v Út 07. 07. 2009 v 15:22 -0500:
> A telco equipment vendor has pointed out that when
> an ACK message pass via our SER servers, a Via: header
> is added which is normal, but frequently the branch value
> in that Via: header is "0".  As in:
> 
> Via: SIP/2.0/UDP 10.133.90.x;branch=0
> 
> This violates RFC 3261 for being zero and for not being
> "unique across time and space".  (8.1.1.7, page 38).
> 
> This is showing up in over 50% of the ACK messages
> being passed through in just one direction.
> When not equal to zero, the value is like this:
> 
> Via: SIP/2.0/UDP 10.133.90.x;branch=z9hG4bK095a.b27ac307.0
> 
> We don't see branch=0 appearing in any other SIP
> message type, just ACKs.
> 
> Is anybody else seeing this and perhaps have a fix?
> 
> The telco equipment vendor doesn't think it is confusing
> their equipment, but as it is out spec they want
> to eliminate it as a source of trouble.
> The calls are originating in a variety of types
> of equipment including Acme, Sonus, Asterisk, etc.
> This is the Via: added by SER, any already present
> when we got the call are non-zero and look fine.
> 
> We are running ser-2.0.0-rc1.
> 
> A sample:
> 
> ACK sip:6x0x9x0x0x;npdi=yes;rn=6x0x6x9x7x at 10.133.0.x:5060 SIP/2.0
> Via: SIP/2.0/UDP 10.1x3.9x.1x;branch=0
> Via: SIP/2.0/UDP 7x.1x.1x3.1x0:5060;branch=z9hG4bK02Bd8a36ba5a45d76d6
> From: <sip:Restricted at 7x.1x.1x3.1x0>;tag=gK020a4ae7
> To: <sip:6103900202 at 2x8.3x.2x1.7x>;tag=000a0285+1+11540020+75d5539b
> Call-ID: 2097284613_75974428 at 7x.1x.1x3.1x0
> CSeq: 15498 ACK
> Max-Forwards: 16
> Content-Length: 0
> 
> Thanks in advance.
> 
> 
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