H3C Technologies H3C MSR 5600 - Manual (Page 97)

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Configuring periodic refresh of SIP sessions
If a proxy server fails to receive a BYE message, it will always retain the state for the session. To solve this
problem, RFC 4082 defines a session refresh mechanism, which periodically sends re-INVITE or UPDATE
requests (referred to as refresh requests) to notify the proxy server of the current session state. The refresh
interval is determined through negotiation between the SIP UA and the SIP proxy server.
Session refresh uses two header fields Session-Expires and Min-SE, and a 422 response:
• Session-Expires—Conveys the maximum session expiration time. If no refresh request is received
within this time, the session is considered ended.
• Min-SE—Conveys the minimum session expiration time, which is used to avoid frequent refresh
requests from occupying excessive network bandwidth.
• 422 response—When a UAS or SIP proxy server receives a request in which the Session-Expires
field conveys a value smaller than the local Min-SE value, the UAS or SIP proxy server sends a 422
response that contains the local Min-SE value to notify the requesting party of the minimum session
expiration time.
To configure periodic refresh of SIP sessions:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter voice view. voice-setup N/A
3. Enter SIP view. sip N/A
4. Enable session refresh. session refresh
By default, session refresh is
disabled if the device acts as a
UAC, and is enabled if the device
acts as a UAS.
Configure this command on the
UAC.
5. Set the maximum session
expiration time and minimum
session expiration time.
min-se time [ session-expires
interval ]
By default, both the maximum
session expiration time and
minimum session expiration time
are 1800 seconds.
Configuring PSTN cause-to-SIP status mappings
The default PSTN cause-to-SIP status mappings are used for communication between a SIP network and
a PSTN. For information about these default mappings, see Voice Command Reference. You can also
change the default mappings to meet specific needs.
To configure PSTN cause-to-SIP status mappings:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter voice view. voice-setup N/A
3. Enter SIP view. sip N/A