Hi, As per RFC-3261, the retry after timer is started by UAC itself after deciding the retry after duration based on call id ownership. So there is no need of retry after header in 491 response code. But since your implementation is as below:
I am adding the party name to make you understand the answer of this query. The call flow is as below: Party A Party B INVITE ----------> B2BUA ----------> INVITE 100 <---------- B2BUA <---------- 100 183 <---------- B2BUA <---------- 183 200 <---------- B2BUA <---------- 200 ACK ----------> B2BUA ----------> ACK <------------Call Established----------> REINVITE-------> B2BUA <-------REINVITE 491 <---------- B2BUA ----------> 491 Here is the two part of the call. 1. Party A --------------------> B2BUA 2. B2BUA --------------------> Party B In first case, Party A is owner of the call id. So B2BUA will send 491 response towards party A with the duration between 2.1 and 4 seconds in retry after header. In second case, Since B2BUA is call id owner so it will send 491 response towards party B with duration between 0 to 2 seconds in retry after header. Regards, Alok Tiwari -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Kamini Gangwani Sent: Friday, October 17, 2008 2:10 PM To: sip-implementors@lists.cs.columbia.edu Cc: Kamini Gangwani Subject: [Sip-implementors] Query regarding Retry-After timers in 491response in glare situation Hi I have one query regarding timers handling in 491 "Request Pending" for Re-Invite. The scenario is like this: A call is being established with an Application which is behaving as B2BUA. Now we receives Reinvite from both sides- UAC and UAS at same time and due to which a glare situation arises and B2BUA sends 491 "Request Pending" to both sides UAC and UAS. So my query is that: what should be the value of Retry-After timer in 491 for both call legs? INVITE ----------> B2BUA ----------> INVITE 100 <---------- B2BUA <---------- 100 183 <---------- B2BUA <---------- 183 200 <---------- B2BUA <---------- 200 ACK ----------> B2BUA ----------> ACK <------------Call Established----------> REINVITE-------> B2BUA <-------REINVITE 491 <---------- B2BUA ----------> 491 (What should be the value of Retry-After timer in 491 response on both sides?) As per RFC-3261, I got this information: "If a UAC receives a 491 response to a re-INVITE, it SHOULD start a timer with a value T chosen as follows: 1. If the UAC is the owner of the Call-ID of the dialog ID (Meaning it generated the value), T has a randomly chosen value between 2.1 and 4 seconds in units of 10 ms. 2. If the UAC is not the owner of the Call-ID of the dialog ID, T has a randomly chosen value of between 0 and 2 seconds in units of 10 ms." But since in case of B2BUA, is it that we should check if it is side-1, then timer value should be 2-4 seconds and if it is side-2, then timer value should be 0-2 seconds. Is this correct understanding or anybody having some other views on this? Regards, kamini gangwani Aricent ________________________________ "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
