In working on specifying and deploying systems that will actually use the RPH with the ets and wps namespaces, we have found several contexts in which the RPH on the response is very useful.
1) Error reporting. RFC 4412 does not give clear direction on the treatment of RPH with syntax errors (out of range priority values, duplicate namespaces, etc.) We have found that including the RPH in the 4xx responses is usesful in addressing the errors. 2) In our system, we often set the ets RPH (with default priority) based on the “ETS-DN”“dialed number” or uri, before authentication and before knowing the correct priority value. Including the RPH in the response is a useful way of conveying the correct priority value back to nodes earlier in the “call flow”. 3) Similarly, if an RP actor receives a SIP INVITE with the ETS-DN, but no RPH it may, after authenticating the call, include RPH in the responses in order to inform nodes earlier in the call flow that this is a priority call. 4) If the RPH is being used to prioritize processing (of both messages and responses) in the SIP user agent, including the RPH in the response allows the receiving RP actor to give the response “ETS treatment” before checking on the “state” of the call. This is particularly relevant when the RP actor itself is congested. Janet "James M. Polk" <[EMAIL PROTECTED]> wrote on 06/16/2007 05:13:37 PM: > SIP WG > > Here is a new ID I've written because of implementation > considerations to allow a SIP Resource-Priority header (RPH) in > responses, which RFC 4412 currently disallows, assuming only that > stateful devices will use RPH. There have been many requests to have > this "only stateful devices" restriction relaxed, in certain > scenarios. This ID does this, and proposes how IANA is changed > accordingly wrt RPH. This ID does nothing else. > > Comments are appreciated. > > >A New Internet-Draft is available from the on-line Internet-Drafts > >directories. > > > > Title : Allowing SIP Resource Priority Header in > > SIP Responses > > Author(s) : J. Polk > > Filename : draft-polk-sip-rph-in-responses-00.txt > > Pages : 6 > > Date : 2007-6-15 > > > > The Session Initiation Protocol (SIP) Resource Priority Header > > (RPH), in its current form, is ignored in SIP responses. This was a > > design choice during RFC 4412's development. This is now considered > > a bad design choice in certain scenarios. This document corrects > > RFC 4412's communications model by optionally allowing a SIP server > > or user agent client to process the Resource-Priority Header in a > > response. > > > >A URL for this Internet-Draft is: > >http://www.ietf.org/internet-drafts/draft-polk-sip-rph-in-responses-00.txt > > > _______________________________________________ > Sip mailing list https://www1.ietf.org/mailman/listinfo/sip > This list is for NEW development of the core SIP Protocol > Use [EMAIL PROTECTED] for questions on current sip > Use [EMAIL PROTECTED] for new developments on the application of sip
_______________________________________________ Sip mailing list https://www1.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
