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Reliability and Recoverability
Issue 5 January 1998
1-15555-230-024
Reliability and Recoverability
The system is designed to recover from a power outage or other failure instantly,
regardless of the source of the failure. Each port network includes a set of
segmented, parallel buses. If one of the paired segments fails, the other bus
segment continues to handle communications. You can always further enhance
the system’s reliability by duplicating critical components such as processors or
fiber-optic links between port networks.
In systems with duplicated control carriers, the entire processor complex is dupli-
cated in the processor cabinet. Should the active elements fail, the standby ele-
ments are instantly activated and assume system control. All in-process calls and
system activities are maintained. New user service is restored in about 10 sec-
onds; application links recover within two seconds.
In addition, all system I/O links also stay operational. These links include support
for the Call Management System, the CallVisor Adjunct/Switch Applications Inter-
face, a Distributed Communications System, and the I
NTUITY AUDIX Voice Mes-
saging System. Redundancy is built into the packet bus, and higher packet bus
reliability can optionally be achieved by adding a maintenance/test circuit pack
to each port network.
Memory shadowing, a unique DEFINITY ECS capability, is a function where the
memory in the standby processor is continuously updated to reflect the memory
in the active processor. This permits the system to change from one processor to
another without any noticeable interruptions in service. Memory shadowing is not
only important for maintaining basic intercom, incoming, and outgoing calls, but
also for complex calling processes such as queuing and call vectoring opera-
tions.
Much of DEFINITY ECS’s reliability and recoverability is attributable to the switch
architecture and the power of the system software. The distributed processor
architecture provides subsystem processors on each circuit pack, for example. A
standard maintenance routine is conducted automatically by the system, as are
periodic backups of translations. All of this inherent reliability/recoverability can
be further enhanced by redundancy in system configuration.
Configuring for Reliability/Recoverability
DEFINITY ECS can be configured to meet the disaster recovery needs of any
business. For example:
■ Calls can be routed through an alternate DEFINITY ECS if one site is
destroyed or disabled by natural or man-made disaster.
■ Multimedia (voice, video, data) connections to the network can all be
made redundant, in case of network failures. The system can be routed
through multiple public exchanges to protect against network failures (a
cable or fiber being cut, for example).