Juan De Stefano <[email protected]> writes: > I have a situation where an SBC is handling non symmetric signalling on > REGISTER process. > (1) The UAC sends REGISTER with Expires=600 to SBC and then SBC sends it to > real Registrar. > (2) The Real Registrar rejects the REGISTER with a 423 Interval too brief > and sends back a Min-Expires=1800, SBC forwards the 423 Response back to > UAC with Min-Expires=1800. > (3) The UAC re-sends the REGISTER with Expires=1800 to SBC and this to real > Registrar. > (4) The real Registrar sends back 200OK with expires=1800 to SBC > (5) SBC forwards the 200OK to the UAC but changes the expires=600 > (6) UAC gets registered. > > What value the UAC should use in Expires header on the next REGSITER > refresh?
The odd thing is that almost any strategy will work successfully, as long as whenever the UAC receives a 423 response it sends another REGISTER with a larger Expires value. In addition to the behavior patterns you listed, there are: When 300 seconds have passed (based on the lease obtained), the UAC sends another REGISTER with Expires of 1800 seconds (based on the previous Min-Expires value). The Registrar responds with Expires of 1800 and the SBC modifies the response to have Expires of 600. The more complicated strategy where the SBC acts as the UAS for the REGISTER requests from the UAC, and as long as the SBC-UAS sees an active registration from UAC, the SBC-UAS maintains a registration for the UAC at the Registrar (giving the UAC's contact address for the UAC's AOR). Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
