[OpenSIPS-Users] Working with MAX-FORWARDS in B2B topology hidding

[Răzvan Crainea]

Hi, Alexey!

Unfortunately the behavior is mis-documented - the Max-Forwards seems to 
always be enforced to 70, regardless what's on the a-leg.
Please open a bug report on our tracking list [1] to keep an eye on this.

[1] https://github.com/OpenSIPS/opensips/issues

Best regards,

Răzvan Crainea
OpenSIPS Core Developer
http://www.opensips-solutions.com

On 4/12/21 2:06 AM, Алексей Хамстр wrote:
> Hello.
> Please tell me who faced the setting of the MAX-FORWARDS parameter pass 
> when using the B2B module
> We have found that when using the module, this counter starts counting 
> again from the initial value of 70, which leads to looping of calls in 
> the network.
> example from trace
> 
> in the input of opensips we have
> 
> INVITE sip:543174317 at 94.241.67.137 
> <mailto:sip%3A543174317 at 94.241.67.137> SIP/2.0
> *Max-Forwards: 18*
> Via: SIP/2.0/UDP 94.241.67.136:5062;rport;branch=z9hG4bK759843122
> From: <sip:212232435 at 94.241.67.136:5062 
> <http://sip:212232435@94.241.67.136:5062>>;tag=298433023
> To: <sip:543174317 at 94.241.67.137 <mailto:sip%3A543174317 at 94.241.67.137>>
> Call-ID: 752394752 at 94.241.67.136:5062 <http://752394752@94.241.67.136:5062>
> CSeq: 3633945 INVITE
> User-Agent: YATE/6.2.1
> Contact: <sip:212232435 at 94.241.67.136:5062 
> <http://sip:212232435@94.241.67.136:5062>>
> Allow: ACK, INVITE, BYE, CANCEL, REGISTER, REFER, OPTIONS, PRACK, INFO
> Supported: 100rel
> Content-Type: multipart/mixed;boundary=734768646_1362544590
> Content-Length: 443
> 
> but on the output there is:
> 
> INVITE sip:543174317 at 94.241.67.137 
> <mailto:sip%3A543174317 at 94.241.67.137> SIP/2.0
> Via: SIP/2.0/UDP 94.241.67.137:5060;branch=z9hG4bK5e7e.38ff3a06.0
> To: sip:543174317 at 94.241.67.137 <mailto:sip%3A543174317 at 94.241.67.137>
> From: <sip:212232435 at 94.241.67.136:5062 
> <http://sip:212232435@94.241.67.136:5062>>;tag=153c35a5fde4948908525582635dfe04
> CSeq: 3633946 INVITE
> Call-ID: B2B.506.2825450.1617906940
> *Max-Forwards: 70*
> Content-Length: 185
> User-Agent: OpenSIPS (2.4.6 (x86_64/linux))
> Content-Type: application/sdp
> Supported: 100rel
> Allow: ACK, INVITE, BYE, CANCEL, REGISTER, REFER, OPTIONS, PRACK, INFO
> Contact: <sip:94.241.67.137:5060 <http://94.241.67.137:5060>>
> 
> The module documentation says that this header should be passed from the 
> dialog of one side to the other side.
> Max-Forwards (it is decreased by 1)
> 
> Thanks in advance,
> with regards,
> Alexey Homstr
> 
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