I have a question about what, if any, SIP behaviour there should be if a UA receives SDP with a connection address expressed as a domain name and which cannot be resolved. In this case at least one, and possibly all, media streams cannot be sent. This is also similar to an ARP failure on a LAN but probably much more likely to occur. There is also a similarity to receiving an ICMP unreachable indication for a media stream in progress. In all cases the media cannot be sent yet the signalling channel, especially in the case of 3PCC, may be unaffected.
If the SDP was in an INVITE, the response could indicate a DNS resolution failure (although no response codes are defined which cover this specific case). But the SDP could also be in either a 2xx response or in an ACK. In these cases, a re-INVITE could be sent following the completion of the INVITE transaction which contained the unresolved name. Alternatively, a BYE could be sent to terminate the session. Finally, the session could be unaffected and corrective actions left to the user which notices a lack of media. Only the BYE seems deterministic since a response to a re-INVITE is likely to contain the same SDP as caused the resolution failure. However it would appear to be too drastic if there were other media streams in the session which did resolve (i.e. the c= which did not resolve was within one of several media descriptions and not at the session level). What is the accepted solution here? Thanks, Tim _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
