That comes down to whether userspace, SIP stack-level OPTIONS pings are a "good estimate of RTT". :-)
-- This message was painstakingly thumbed out on my mobile, so apologies for brevity and errors. Alex Balashov - Principal Evariste Systems LLC 235 E Ponce de Leon Ave Suite 106 Atlanta, GA 30030 Tel: +1-678-954-0670 Fax: +1-404-961-1892 Web: http://www.evaristesys.com/, http://www.alexbalashov.com On May 23, 2012, at 5:28 PM, "Olle E. Johansson" <o...@edvina.net> wrote: > > 23 maj 2012 kl. 14:21 skrev Kevin P. Fleming: > >> While this behavior is technically not RFC3261 compliant (and I've had >> discussions about it with at least one of the RFC's authors), it's quite >> useful in making decisions about whether a peer has become unavailable more >> quickly than would normally be possible. For a local peer that responds to >> OPTIONS requests in 100ms or less, if that peer stops responding, Asterisk >> will be able to make that determination in approximately 6 seconds, instead >> of the 32 seconds that would normally be required. > > Form the RFC: > > "T1 is an estimate of the round-trip time (RTT), and it defaults to 500 ms." > > "The default value for T1 is 500 ms. T1 is an estimate of the RTT between the > client and server transactions. > Elements MAY (though it is NOT RECOMMENDED ) use smaller values of T1 within > closed, private networks > that do not permit general Internet connection. T1 MAY be chosen larger, and > this is RECOMMENDED if it > is known in advance (such as on high latency access links) that the RTT is > larger. Whatever the value of T1, > the exponential backoffs on retransmissions described in this section MUST be > used." > > I can't see how this is not RFC 3261 compliant. We have a good estimate of > the RTT and use it. > > /O > -- > _____________________________________________________________________ > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > > asterisk-biz mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-biz -- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-biz mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-biz
