On 11/17/03 12:07 PM, "Vijay K. Gurbani" <[EMAIL PROTECTED]> wrote:
> Franz Gober wrote: > >> We have a discussion about "optional or mandatory" in relation to the >> tag "transport=tcp" in the contact header and the meaning of TCP in the >> VIA header. In RFC2543 and 3261 there is no clear message how it should >> work. >> Exactly: Is the "transport=tcp" tag in the contact field always mandatory if >> the optional header field "Contact" is used. > > Note that the Contact field is NOT optional in INVITE and 200 OK > (INVITE); see Table 2, rfc3261. Basically any request that > establishes a session (and this includes SUBSCRIBE) needs to > insert a Contact field. > >> The underneath transaction is >> done in one TCP connection and it is working with most of end devices. >> But one end device is switching back to UDP for the ACK message because >> there is no "transport=tcp" at least in the 200 OK >> message. > > This behavior is what you will get and is correct under the > current implementation of the protocol. The default transport > for SIP is UDP (see Table 1, rfc3261) and most implementations > support UDP more readily than they do TCP. Thus, absence any > 'transport=tcp' guidelines, they will revert to UDP. > if you are doing NAPTR you may end up with TCP even with no transport=tcp _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
