Hi Basu,
in RFC3311 section 5.3,
If a UAC receives a 491 response to a UPDATE, it SHOULD start a timer
with a value T chosen as follows:
1. If the UAC is the owner of the Call-ID of the dialog ID
(meaning it generated the value), T has a randomly chosen value
between 2.1 and 4 seconds in units of 10 ms.
2. If the UAC is not the owner of the Call-ID of the dialog ID, T
has a randomly chosen value between 0 and 2 seconds in units of
10 ms.
Regards,
Shinji
On 2020/09/18 17:38, Basu Chikkalli wrote:
Hi All,
A--------------------->B2BUA------------------------>B
Considering B2BUA and B-Party into session refresh.
Both B2BUA and B support timer.
Refresher is: B2BUA
on 1800/2=900sec, B2BUA sends refresh UPDATE
B2BUA ---------UPDATE----------->B
B2BUA<--------491----------------B
Due to race condition, B sends 491
Queries:
1. B2BUA retries next after some interval, if again B-Party sends with
491. B2BUA should send BYE to the session?
2. How long/how many times should B2BUA should retry? when it should
terminate the session.
Extracted RFC4028 says,
If the session refresh request transaction times out or generates a
408 or 481 response, then the UAC sends a BYE request as per
Section <https://tools.ietf.org/html/rfc3261#section-12.2.1.2>
12.2.1.2 of RFC 3261
<https://tools.ietf.org/html/rfc3261#section-12.2.1.2> [2
<https://tools.ietf.org/html/rfc4028#ref-2>]. If the session refresh
request does not
generate a 2xx response (and, as a result, the session is not
refreshed), and a response other than 408 or 481 is received, the UAC
SHOULD follow the rules specific to that response code and retry if
possible.
Thanks
Basaw
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