Error responses (3xx,4xx,5xx, and 6xx) are hop-by-hop. The proxy must always send the ACK to an error response. Only the ACK for a success (2xx) response is sent end-to-end. A proxy is suppose to send only one error response back to the UAC(A). Also, the proxy does not forward an ACK to an error response. Since the proxy has already sent a 480, it should not send the 487 from the UAS(B).
See section 16.7 of RFC 3261 for more details of proxy response handling behavior. cheers, (-:bob Robert F. Penfield Chief Software Architect Acme Packet, Inc. 71 Third Avenue Burlington, MA 01803 [EMAIL PROTECTED] ----- Original Message ----- From: "Venkatesh Joshi" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: <[email protected]> Sent: Thursday, May 04, 2006 3:13 AM Subject: Re: [Sip-implementors] question on the behavior of 487 message. > Hi Santosh, > > Thanks a ton! > > A follow-up question - Does the sip proxy "generate" an ACK on receiving > the 487 from B ? > Or does it "forward" the ACK sent by A (which sends the ACK on receiving > the 487) ? > > The issue is that in the the product on which I am working, the > requirement is that we > should intercept the 487 that comes from the proxy to A. We should not let > the 487 reach > A. Hence, I am wondering if we should also send an ACK on behalf of A > after receiving (and > dropping) the 487 destined to A. > > thanks, > Venkatesh > > [EMAIL PROTECTED] wrote: >> >> Hi Venkatesh, >> >> Ideally proxy should send ACK for 487 Request Terminated. >> It seems like Ondo Sip server is misbehaving. >> >> >> >> Thanks and Regards, >> Santosh >> >> >> >> >> >> >> *Venkatesh Joshi <[EMAIL PROTECTED]>* >> Sent by: [EMAIL PROTECTED] >> >> 05/04/2006 11:11 AM >> >> >> To >> [email protected] >> cc >> Venkatesh Joshi <[EMAIL PROTECTED]> >> Subject >> [Sip-implementors] question on the behavior of 487 message. >> >> >> >> >> >> >> >> >> Hi, >> >> I have the following requirement: >> >> A calls B. If B doesn't answer the call within a configurable period of >> time, we should >> disconnect the call. >> >> For this, we send a 480 message to A and a CANCEL message to B. The flow >> sequence of >> messages is like: >> >> A Proxy >> <---------------- (480 not available) >> (ACK) ----------------> >> >> >> Proxy B >> (CANCEL) --------------------> >> <-------------------- (200 OK) >> <-------------------- (487 Terminated) >> (ACK) ---------------------> [NOT BEING SENT] >> >> However, the problem is that multiple "487 Request Terminated" messages >> are coming from B. >> >> I think this is because the proxy doesn't send the ACK for the 487 >> message at all. Is this >> the normal behavior ? I am using the Ondo Sip server. >> >> thanks, >> Venkatesh >> >> _______________________________________________ >> Sip-implementors mailing list >> [email protected] >> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >> >> >> >> *********************** FSS-Unclassified *********************** > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
