Comments in line. -- Dai
-----Original Message----- From: Paul Kyzivat [mailto:[EMAIL PROTECTED]] Sent: Friday, October 12, 2001 10:22 AM To: [EMAIL PROTECTED] Subject: [Sip-implementors] Re: Need clarification on callerprefs I have another question about callerprefs, in addition to the earlier messages I have posted on this subject. This is primarily a question about the handling of REGISTER by a registrar, but the question only makes sense in the context of the changes to the Contact header proposed in draft-ietf-sip-callerprefs-04. Section 5.1 says: "This specification adds the following extension parameters to the Contact header field ... These parameters apply to a single URI. When used in a Contact header, they specify characteristics of the URI in the header." Now, suppose I want to specify that a given URI is fully capable in English and slightly capable in Spanish. This is a reasonable thing to want to specify, and there seems to be a way to do it: Contact: sip:[EMAIL PROTECTED]; language="en"; q=1.0, sip:[EMAIL PROTECTED]; language="es"; q=0.2 My question is: is this a legal construction in a Contact header? >>>>>> yes. Normally, if there had been a prior registration of Contact: sip:[EMAIL PROTECTED]; language="en"; q=1.0 and a new registration was received containing Contact: sip:[EMAIL PROTECTED]; language="es"; q=0.2 then the new contact would *replace* the old one. >>>>>> No. These are two different contacts because the language parameter is used for matching. As far as I can tell, the bis is silent on what should happen if two contacts with the same URI are present in the same register request. I can see three possible interpretations: 1) upon receipt of the REGISTER request, the registrar first removes any previously registered contact entries that match any of the contact entries in this REGISTER request. Then all the contact entries in this register request are saved. 2) a REGISTER request with multiple contact entries is processed much like multiple REGISTER requests each with a single contact entry. If two contact entries mention the same URI, each one in turn replaces the previous one. Only the last remains. No error occurs. >>>>> I think this is the current behavior. 3) a REGISTER request with multiple contact entries containing the same URI is considered erroneous, and results in an error such as 400 Bad Request. Of these, (1) is compatible with the example above while the others aren't. (2) is a silly interpretation - it is never useful. (3) forbids a useful application and is extra work to detect. I would like to see a clarification somewhere that (1) is the required behavior. I don't know if this belongs in draft-ietf-sip-rfc2543bis-*, or in draft-ietf-sip-callerprefs-*. Thanks, Paul Kyzivat Cisco Systems _______________________________________________ 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
