Nortel Meridian Meridian 1 Feature Description And Administration page 1408

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553-2901-301 Standard 9.00 January 2002
Network Time Synchronization
To provide Time Synchronization on a network-wide basis, Meridian
Customer Defined Integrated Services Digital Network (ISDN) nodes can
request Time Synchronization from another node, using D-channel messages.
Therefore, Slave switches can request the time from the Master switch, while
the Master switch can do the same to a Backup node.
A time difference (or delta) is provided for every node, in order to distinguish
time zones for time usage by local features (e.g., Automatic Wake-up) and
centralized ones (e.g., Centralized Call Detail Recording).
The Time Synchronization request messages are composed of:
• the message identifier
• the requester's ID
• the time
• the date
• the time-adjust factor
IDs are virtual DNs, and are used to route the messages.
On the Slaves, Time Synchronization requests are sent automatically under
the background routines (default setup) or with the daily routines (optional
setup), every time a time change is performed (to accurately set the seconds),
and on every SYSLOAD and initialization.
On the Master, Time Synchronization requests are sent to a Backup node
upon initialization and, therefore, after SYSLOAD. The Master will be
forbidden to synchronize Slave switches during these backup periods. In the
rare event where Master and Backup nodes would start requesting
synchronization at the same time, the real time will be considered to be on the
Slave node, if it is not initializing. If both nodes are only initializing, the real
time would be considered to be carried by the Master switch. If a SYSLOAD
occurs at the Master and the Slave is initializing, the real time would be
considered to be carried by the Slave switch. A warning message will be
printed if both switches SYSLOAD, and all Time Synchronization would be
put to a halt until the Master's clock is reset.