Media5 Mediatrix 4104, Reference Manual

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Session Timers Reference Manual (SIP Version)
Mediatrix 4104 259
Session Timers
The session timer extension allows to detect the premature end of a call caused by a network problem or a
peer’s failure by resending an INVITE at every
n seconds.
A successful response (200 OK) to this INVITE indicates that the peer is still alive and reachable. A timeout
to this INVITE may mean that there are problems in the signalling path or that the peer is no longer available.
In that case, the call is shut down by using normal SIP means.

To set Session Timer information:
1. In the sipUAIfTable group, set the session timer maximum expiration delay in the
sipUAMaximumSessionExpirationDelay variable.
This is the suggested maximum time, in seconds, for the periodical session refreshes. It must be
equal to or greater than the minimum value. This value is reflected in the
Session-Expires header.
2. Set the session timer minimum expiration delay in the sipUAMinimumSessionExpirationDelay
variable.
This is the minimum value, in seconds, for the periodical session refreshes. It must be equal to or
smaller than the maximum value. This value is reflected in the
Min-SE header.
The Min-SE value is a threshold under which proxies and user agents on the signalling path are not
allowed to go.

To disable the Session Timer service:
1. Set the sipUAMaximumSessionExpirationDelay variable to 0 .
Increasing the maximum helps to reduce network traffic, but also makes “dead” calls longer to
detect.
Session Timer Version
You can select the version of the session timer draft that the Mediatrix 4104 uses. Session timer versions other
than those provisioned may not work because of backward compatibility issues between the versions.
This feature is currently located under the mediatrixExperimental branch of the MIB structure. See “MIB
Structure” on page 133 for more details.
The Mediatrix 4104 supports the following session timer versions:

To set the version of session timers supported:
1. In the sipInteropMIB , set the sipInteropSessionTimersVersion variable with the proper version.
• sessionTimer04
• sessionTimer08
Standards Supported • draft-ietf-sip-session-timer-08.txt
• draft-ietf-sip-session-timer-04.txt (expired)
Table 164: Session Timer Versions Supported
Version Description
sessionTimer04 The Mediatrix 4104 uses the session timer extension as described in the now expired
draft-ietf-sip-session-timer-04.txt . Its use is deprecated. You should use this setting for
backwards compatibility issues only.
sessionTimer08 The Mediatrix 4104 uses the session timer extension as described in the more recent
draft-ietf-sip-session-timer-08.txt . This draft version contains several enhancements over
the previous ones, including the use of the Min-SE header. Use this setting if you do not
need to interoperate with session timer v4-enabled parties.