Hi, inline..
On 5/23/06, Nataraju A B <[EMAIL PROTECTED]> wrote: > Comments inline... > > Thanks & Regards, > Nataraju A.B. > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Sachin > Srivastava > Sent: Monday, May 15, 2006 5:30 PM > To: [email protected] > Subject: [Sip-implementors] A Query from RFC 3262 > > Hi, > > > > > > I have a query regarding the following excerpt from the RFC 3262. > > > "An element that can act as a proxy can also send reliable provisional > responses. In this case, it acts as a UAS for purposes of that > transaction. However, it MUST NOT attempt to do so for any request that > contains a tag in the To field. That is, a proxy cannot generate > reliable provisional responses to requests sent within the context of a > dialog." > > > > [ABN] this may not be the complete answer to your question but partly > goes like this... > If this request is WITHIN a dialog, it does mean that the target is some > downstream and hence only UAS can send any provisional responses > reliably and proxies will do the functionality of 'proxy' alone. > > Q1. In which condition/scenario can a Proxy server send reliable > provisional response? > > [ABN] If this is a request outside a dialog then it might so happen that > proxy may need to send the provisional response before actually the UAS > can reply to this request. > > For instance, consider the following scenario... > 1. Proxy got multiple contacts to tryout after LS query (assuming this > is a inbound-proxy) > > 2. Received user busy response from one of the contact, > 3. User had set the call forwarding on busy feature. > > > In this scenario proxy might decide to send the provisional response > reliably to the caller and in the mean time it can retry to other > contacts. > > [ABN] Please correct me if I am wrong here... > <<Amar>>generation of reliable provisional response is not meant for Proxies. As the tag in the 18x reliable must be same as that of response to the INVITE. In the above case proxy can't generate the To-tag on the behalf of the callee. If it does so, then on the caller (UAC) side dialog info created by 18x reliable response will not match to the final response to the INVITE (ie. different To-tags in 18x and 200 OK to INVITE). So In the above case(1) proxy can't generate reliable 18x response. But it can be feasible for a B2BUA or 3pcc controller. Same Tag issue happens with case 2 & 3. But bigger problem happens when INVITE is received without SDP. Now as a Proxy we can't send SDP on behalf of callee. If proxy tries to send 18x then it will violet rfc3262 3262 is not quite clear about this except the statement "An element that can act as a proxy can also send reliable provisional responses." which infers that the element can be a 3pcc or B2BUA not a pure proxy. > Q2. Is there any specific implementation needed for Proxy from this RFC? > <<Amar>> If the proxy is a TSP then 3262 implementation , may not be required. If it is Call stateful then offer answer needs tobe taken care. > [ABN] Not sure > > Thanks & Regards, > > Sachin Srivastava > > > > _______________________________________________ > 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 > -- Rgds, Amar Mobile: +919886395894 The greatest enemy of best is "good." If you're willing to accept "good" you'll never be the "Best." _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
