Avaya S8700 Maintenance Manual page 2386

Maintenance-Object Repair Procedures
Software Instigated Tone-Clock Interchanges
Tone-Clock interchanges may be initiated by software in three ways:
1. A scheduled Tone-Clock or IPSI circuit pack interchange occurs according
to the parameters set by the change system-parameters maintenance
command. This parameter can be disabled or set to run weekly, the default
is for it to occur daily, at a time specified in the system-parameters list for
scheduled maintenance to begin. This interchange will be blocked, if the
non-preferred Tone-Clock or IPSI circuit pack in an EPN that has been
selected with the set tone-clock or set ipserver-interface command.
Also if the standby Tone-Clock or IPSI has been set to the busyout state, or
if the clock generation capability is known to be impaired. When this
scheduled interchange occurs, the standby Tone-Clock or IPSI circuit pack
becomes active for twenty seconds to test its ability to generate clock
signals. For IPSI scheduled interchanges, the other IPSI modules located
on the IPSI circuit pack, i.e. the Packet interface and Archangel are also
tested. After testing the IPSI is returned to standby mode.
For Non-IPSI Port Networks, unscheduled interchanges occur when
on-board Tone-Clock circuit-pack maintenance, or ongoing switch
maintenance test of the TONE-BD, TONE-PT or the TDM-CLK uncover
failures serious enough to raise a MAJOR or MINOR alarm against the
active IPSI or Tone-Clock circuit pack.
For IPSI Port Networks, unscheduled IPSI/Tone-Clock interchanges may
occur any time as a part of an unscheduled IPSI interchange. The IPSI
interchange may be the result of Tone-Clock, PKT-INT, or EAL faults.
2. In an EPN with duplicated Tone-Clock or IPSI circuit packs, one circuit pack
is always preferred over the other. For the first port network in a cabinet,
this is the Tone-Clock or IPSI circuit pack in carrier A. If a second port
network is configured in a cabinet, its preferred Tone-Clock or IPSI circuit
pack is located in carrier E. The intention is that if the preferred Tone-Clock
or IPSI circuit pack has been replaced or repaired, the system will make it
active by interchanging to it as soon as possible.
Firmware Instigated Tone-Clock Interchanges
Firmware-initiated Tone-Clock interchanges occur when the auto clock switching
option is enabled, and the TN2312 IPSI circuit pack firmware detects a loss of
clock or clock errors. After detecting a loss of clock/clock errors, and rather than
waiting for S8700 Multi-Connect software to request a switch, the IPSI firmware
will automatically switch the clock (when auto clock switching is enabled). The
auto clock switching option is disabled during system restarts.
NOTE:
The auto clock switching option is required by the IPSI circuit pack since the
EAL connection to the PKT-INT (one of the IPSI circuit packs many
functions) is over the S8700 Multi-Connect packet bus which must have a
good clock for proper operation.
8-1664 Issue 1 May 2002 555-233-143