Avaya 03-300430 User Manual

Note:

Refer to 

 in Maintenance Procedures 

(03-300192) for MMCH troubleshooting information.

Each Port Network (PN) must have a TN787D or later MMI circuit pack assigned as the 
Multimedia Interface (MMI) master synchronization source for that PN. If one or more MMI 
circuit pack is administered in a PN, one MMI circuit pack is designated as the master 
synchronization source for every MMI circuit pack within that PN.
The MMI circuit pack generates a synchronization signal and puts that signal on the TDM bus. 
Other MMI packs or any other circuit pack within a PN can listen to this signal and “synchronize 
up” to it. The first MMI circuit pack inserted in a PN is normally designated as the master. As 
subsequent MMI packs are inserted, they are instructed to listen and synchronize to the 
time-slot of the master MMI. In the unlikely case of an MMI losing this reference, an uplink 
message is sent from the MMI circuit pack that lost the signal to maintenance, which also clears 
the “event” counter on this MMI with a downlink message. This forces the MMI circuit pack to 
return the current state of the synchronization signal. If the signal is still lost, then the recovery 
algorithm is entered. Note that during this time, the MMI circuit pack synchronizes to its internal 
clock, and there should be no service disruption. A loss of synchronization is usually the result 
of a circuit pack failure. The maintenance strategy is to switch the master source away from the 
bad pack to another healthy MMI circuit pack within the PN.
A synchronization switch takes place if half or more of the MMI circuit packs in a PN report a 
loss of synchronization. For example, a PN with two MMIs reporting a loss of sync source 
switches immediately, three and four MMIs switch if two report the loss, and so forth. A healthy 
MMI circuit pack becomes the master synchronization source providing the signal on a new 
timeslot. The other MMI circuit packs within the PN are instructed to listen to this new signal, 
and the old master stops providing the signal and now listens to the new master MMI. If an MMI 
is physically removed from the system, then the remaining MMIs report the loss of 
synchronization. The first MMI with no alarms present becomes the new master of that PN. 
Once a synchronization switch has occurred, another switch is not allowed for 15 minutes to 
avoid hyperactive switching. If every MMI has an alarm, then no switch is made.
If the MMI circuit pack that provides synchronization is craft busied out, it will not affect the PN 
synchronization. The signal is still provided by the busied-out pack. There is no effect on 
synchronization if the technician enters a release of the busied-out MMI. Synchronization is not 
affected by a warm start of the system (reset system 1). For every other restart (reboot through 
cold 2), MMI synchronization recovers during board insertion.

MMI-SYNC

MIN

test board location l r#

Multimedia Interface circuit pack