Chapter 9: System Failover And Survivability; Supporting Survivability - Avaya 9608 Administration

Chapter 9: System failover and survivability

Supporting survivability

SIP software provides support for simultaneous calls from multiple servers to accommodate
situations that can occur due to network or server failures. This support ensures that contact
data is preserved and actionable during failover transition, active calls continue, and that much
of the deskphone functionality is available. The following secondary gateways are supported:
Avaya Secure Router 2330 and 4134
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Audiocodes MP-series analog and BRI gateways; Audiocodes MP-series using SIP over
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TCP or TLS for signaling (UDP is not recommended for signaling) and RTP or SRTP for
media
Expanded survivability to Avaya Aura
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The deskphone registers simultaneously to Session Manager and a survivable remote server to
facilitate faster failover or failback transitions than that of the failover solutions offered in
previous SIP software releases and provides minimal disruption from an end user viewpoint.
Contact caching and caching limits in a Session Manager environment are supported. Multiple
operations on a cached contact are not allowed. Preserved media connections or calls are
supported. During failover, changes to applications other than Contacts are cached and are
updated by the PPM with which the deskphone successfully registers.
If the SIP connection recovery is in progress due to a brief network outage, the deskphone
attempts to recover its XMPP connection to Presence Server automatically by re-logging in to
Presence Server. If Presence Server is unreachable, Presence will not be available. If the
connection recovery fails, the deskphone displays an error message.
With non-AST controllers, contact data is cached until the maximum cache size of 25 contacts is
reached; configuration data is cached without limitations. With Session Manager, the PPMs are
in sync and the data is sent to the PPM; data is cached only in case of failure.
Moving subscriptions to a secondary Session Manager or BSM for simultaneous registration
has the following effects on call states and transitions:
Transition from one Session Manager to another Session Manager or BSM is comprised
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of:
- Limbo - The deskphone has lost its connection to its primary controller, but has not yet
detected this regardless of whether a user is on a call or not.
- Moving Subscriptions Interval (MSI) - The deskphone has detected a lost connection to
the primary controller and since it has already registered with a non-primary controller,
this is the brief interval between limbo and successful subscription to the non-primary
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Session Manager
Issue 3 January 2014 151