> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Bob Penfield > Sent: 14 October 2008 15:41 > To: Christer Holmberg; Juha Heinanen; [email protected]; Paul > Kyzivat; Dean Willis > Subject: Re: [Sip] Dual registration without Outbound > > For both GRUU and Outbound a given instance-id > (+sip-instance) actually represents a single UA contact > instance rather than just a single User Agent. The basic idea > behind GRUU is that a request addressed to a GRUU is > forwarded by the proxy to a specific Contact address. The > goal is the same with Outbound but it adds multiple > flows/paths to that UA Contact. This is reflected in the > proxy procedures in both GRUU and Outbound. > > In both cases, the proxy does serial forking to Contacts with > the same instance-id. > > For GRUU it starts with the most-recently registered binding > (according to section 6.1 of GRUU): > > The proxy MUST select the most recently refreshed > contact. As with draft-ietf-sip-outbound, if a request to this > target fails with a 408 (Request Timeout) or 430 (Flow Failed) > response, the proxy SHOULD retry with the next most recently > refreshed contact. Furthermore, if the request fails with any > other response, the proxy MUST NOT retry on any other contacts > for this instance. > > For Outbound, it attempts the registered flows (according to > section 7 of Outbound): > > When a proxy uses the location service to look up a registration > binding and then proxies a request to a particular contact, it > selects a contact to use normally, with a few additional rules: > > o The proxy MUST NOT populate the target set with more than one > contact with the same AOR and instance-id at a time. > o If a request for a particular AOR and instance-id fails > with a 430 > (Flow Failed) response, the proxy SHOULD replace the > failed branch > with another target (if one is available) with the same AOR and > instance-id, but a different reg-id. > o If the proxy receives a final response from a branch > other than a > 408 (Request Timeout) or a 430 (Flow Failed) response, the proxy > MUST NOT forward the same request to another target representing > the same AOR and instance-id. The targeted instance has already > provided its response. > > Therefore, a User Agent that is registering multiple Contacts > to allow the possibility of parallel forking would need to > have a separate instance-id for each Contact. > > For User Agent's that have multiple interfaces, it could use > the MAC address of each interface to create a unique UUID URN > for each contact. > > Thus, the following scenario is possible: > > UA_Contact_wlan;+sip-instance=ID_1;reg-id=1 ----- OB_1 ----- REG_1 > UA_Contact_wlan;+sip-instance=ID_1;reg-id=2 ----- OB_2 ----- REG_2 > UA_Contact_3g;+sip-instance=ID_2;reg-id=1 ----- OB_1 ----- REG_1 > UA_Contact_3g;+sip-instance=ID_2;reg-id=2 ----- OB_2 ----- REG_2 > > Unfortunately, the current text in section 4.1 says that a UA > has "an Instance Identifier". [JRE] In an earlier email I was trying to say roughly the same thing, except the way I looked at it was that a device with multiple interfaces would logically contain a UA for each interface, and each UA would than have a single instance ID. In that case the text in section 4.1 still works.
John _______________________________________________ Sip mailing list https://www.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
