I don't think so. If you send a REGISTER message with a Contact header containing a transport=udp parameter and someone send you an INVITE using TCP it is their problem and not yours. Of course, if the registrar in question require TCP you have a problem unless you can send that REGISTER message using TCP. However, the registrar might accept both TCP and UDP and then you can send a REGISTER message using UDP containing a transport=udp in the contact field and the registrar should be assumed to send any INVITE to you through UDP and never through TCP.
Similarly, you can choose to implement only TCP and again, provided the registrar support TCP you can send a REGISTER message with a Contact header containing a transport=tcp parameter and you should expect to get all INVITEs via TCP and never from UDP. If you do not specify a transport parameter, the registrar might try either method until it gets contact and might then remember which form to try first next time. Again, you can choose to implement only one although in this case you should probably support both. For a proxy or registrar you should probably support both unless you are sure that all parties connected to you uses only UDP or only TCP in which case you can opt to support only that option. For example a proxy that also act as a registrar for a selected number of devices all using UDP and for gateways again only using UDP, you can probably get away with a UDP only solution. Of course, you should be generous in what you accept and in that respect it is never a bad idea to support both. Just saying that the RFC 3261 describe in detail how you can support both but does not really mandate that you do support both in all cases. Some simple telephone devices might only support UDP for example. Alf On Tue, 2006-10-03 at 10:25 -0400, Sanjay Sinha (sanjsinh) wrote: > According to RFC 3261, both UDP and TCP must be supported > > Sanjay > > >-----Original Message----- > >From: [EMAIL PROTECTED] > >[mailto:[EMAIL PROTECTED] On Behalf Of > >Man-Chi Leung > >Sent: Tuesday, October 03, 2006 8:35 AM > >To: [email protected] > >Subject: [Sip-implementors] compare UDP and TCP for sip implementation? > > > >hi all, > > > >I would like to compare/ evaluate the pros and cons on > >implementing SIP based on UDP or TCP. > > > >I do have a bit of confusion on the advantages and > >disadvantages for UDP and TCP in SIP signalling aspect. > > > >primaryly, my solution is very much based on UDP, which I > >believe is commonly used in SIP. > > > >can anyone give me advice? > > > >-------------------------------- > >SIP signalling Channel > >-------------------------------- > >UDP : > >- possibly NAT traveral when both UAs are behind NAT > >- easier to manage UDP connection? > > > >TCP > >- unable to do NAT traveral without relay when both UAs are behind NAT? > >- harder to manage TCP connection for SIP proxy? > > > >--------------------- > >Media Channel > >--------------------- > >UDP: > >- streaming audio/video for media channel > > > >TCP: > >- file transfer > > > > > >~manchi > > > > > >_______________________________________________ > >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 _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
