Folks should note that it is, in fact, necessary for there to be Route headers in CANCEL in some cases. This was discovered recently as a problem and will be corrected in bis-06.
Basically, if a request had Route headers, the CANCEL for that request (and ACK for non-2xx) have the same ROute set. Without that, a stateless proxy would not know how to forward a CANCEL, if the original request was forwarded based on Route headers. This will happen if (1) the original INVITE had pre-loaded route headers, or (2) a re-INVITE is used. -Jonathan R. Christer Holmberg wrote: > Hi, > > Just a small point. > > If your INVITE didn't have Route headers, the CANCEL must not have them > either - no matter if you have received 18x or not. > > Regards, > > Christer Holmberg > Ericsson Finland > > > Ganesh Jayadevan wrote: > >>An initiutive explanation could be that, since a >>CANCEL may be sent out before receiving a '180 >>Ringing' route headers cannot be present in the >>CANCEL. >>Between the time an INVITE is sent out and the receipt >>of response from the remote end, there is no route-set >>(it can only be formed when a response from the remote >>end is recd). Therefore a CANCEL must rely on a >>mechanism separate from the route headers thus forcing >>incomplete transactions in the proxy to keep track of >>the next hop to which the request was sent. >> >> >>>Vikram, >>> >>>If the proxy is stateful, then the transaction state >>>tells the proxy where >>>it sent the request. The proxy will have one or more >>>client transactions >>>associated with a server transaction (See Figure 3 in >>>section 16.2 of >>>bis-05). A stateful proxy must retain these until the >>>transaction completes. >>>If the transaction has completed, then the CANCEL is >>>too late and does not >>>need to be forwarded. >>> >>>cheers, >>>(-:bob >>> >>Robert F. Penfield >>Chief Software Architect >>Acme Packet, Inc. >>130 New Boston Street >>Woburn, MA 01801 >>[EMAIL PROTECTED] >> >>__________________________________________________ >>Do You Yahoo!? >>Send your FREE holiday greetings online! >>http://greetings.yahoo.com >>_______________________________________________ >>Sip-implementors mailing list >>[EMAIL PROTECTED] >>http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors >> > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > -- Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Avenue Chief Scientist First Floor dynamicsoft East Hanover, NJ 07936 [EMAIL PROTECTED] FAX: (973) 952-5050 http://www.jdrosen.net PH: (973) 952-5000 http://www.dynamicsoft.com _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
