[Sip-implementors] When local Min-SE is greater than remote Min-SE

[Tarun2 Gupta]

Hi

What should be the behavior of an UAS upon receiving an INVITE request with Supported:timer, no Session-Expires header and a Min-SE header with a value lower than the configured value of Min-SE?

UAC ----> INVITE with Min-SE: 90 -----> UAS ( Configured Min-SE: 100)

Regards
Tarun Gupta

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[Brett Tate]

Post by Tarun2 Gupta
What should be the behavior of an UAS upon receiving an INVITE
request with Supported:timer, no Session-Expires header and a
Min-SE header with a value lower than the configured value of
Min-SE?
UAC ----> INVITE with Min-SE: 90 -----> UAS ( Configured Min-SE: 100)

The following snippets are applicable. Concerning the locally configured
Min-SE in relation to locally configured preferred Session-Expires (if
that is the question), my understanding is that the RFC leaves it up to
the vendors to decide if the locally configured Min-SE would or would not
override the locally preferred Session-Expires (especially since it is
likely an atypical configuration for the local preferred to be lower than
the local minimum).

RFC 4028 section 9:

"If the incoming request contains a Supported header field with a
value 'timer' but does not contain a Session-Expires header, it means
that the UAS is indicating support for timers but is not requesting
one. The UAS may request a session timer in the 2XX response by
including a Session-Expires header field. The value MUST NOT be set
to a duration lower than the value in the Min-SE header field in the
request, if it is present."

"The fourth row of Table 2 describes a case where both the UAC and UAS
support the session timer extension, and where the UAC did not select
who will perform refreshes. This allows the UAS to decide whether it
or the UAC will perform the refreshes."