[asterisk-biz] Quote for feature: Check to see if a peer is up

[Kevin P. Fleming]

On 05/23/2012 07:09 AM, Alex Balashov wrote:
> You mean Asterisk uses a Timer T1 value of 250 by default? Or just for OPTIONS requests?

Neither. If 'qualify' is enabled for a peer, the T1 timer for that peer 
is reduced to the average of its response time to the OPTIONS pings that 
'qualify' generates (with a default minimum of 100ms). This behavior can 
be overridden by changing the minimum T1 timer value as I posted previously.

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.

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
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