> -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Dale > Worley > Sent: Thursday, March 05, 2009 10:26 AM > > On Thu, 2009-03-05 at 08:16 +0000, Elwell, John wrote: > > What about non-INVITEs? Provisional responses are designed for INVITEs > > and I am not certain about their applicability to non-INVITEs. > > Yes, provisional responses to non-INVITEs may be slightly out of > specification, but I don't expect any SIP element to malfunction if it > receives a provisional response to a non-INVITE request. OTOH, I would > expect most uses of 'trace' to be attached to INVITEs, although that > makes me think that tracing an OPTIONS might be a useful test tool.
OPTIONS doesn't always get routed through the same path as INVITE, fwiw. > (Which leads to an unexpected observation: RFC 3261 presupposes that > all non-INVITE responses are processed promptly, but in the face of > transport errors, this is not always so. In sipX, we've adjusted > transaction handling so that if a re-send of a non-INVITE message is > seen the recipient sends a 100 to quench further re-sends. It seems to > work exactly as expected, and noticeably reduces re-sends in situations > with transport errors.) I agree for most methods, but we've seen problems with 100 for the OPTIONS. Some devices use the OPTIONS as a reachability ping/test, so sometimes the 100 makes them think the far-end is reachable even if they get a 408 later; in other cases some devices look for specific response codes to detect administrative out-of-service, for example a 500/503 to an OPTIONS sometimes is used for that, and sometimes they didn't code for the 100 Trying as being a possibility, so they see it and assume it's not out-of-service, and the 503 sent later doesn't get processed the same. I consider these bugs/broken implementations, but just noting sending the 100 is not bug-free. -hadriel _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [email protected] for questions on current sip Use [email protected] for new developments on the application of sip
