Clock Source For Isdn Cards - Nortel ICS Install Manual

Clock source for ISDN cards

Systems with ISDN interfaces need to synchronize clocking
with the ISDN network and any connected ISDN terminal
equipment. Clocking synchronization is supported by either a
Combination Fiber 6-port Services Cartridge or a Services
Cartridge.
The Modular ICS derives timing from the network using
U-NT and T reference points (loops). Terminal equipment on
U-LT and S reference points (loops) derive timing from the
ICS.
Systems synchronize clocking to the first-available functional
network connection. If there are excessive errors on the
reference network connection, or if the loop fails, the next-
available functional network connection is used for clock
synchronization.
The clock synchronization process generates alarm codes and
event messages. See the Alarm codes on page 548 and Event
messages on page 555 for more information.
When you configure the network connections to the Modular
ICS, you should take into account the system preferences for
selecting loops for synchronization:
• lower numbered loops have preference over higher
numbered loops
• the loop preference order is: 201, 202, 203, 204, 225, 226,
227, 228 (Profile 1, 3 and 4), or 201, 202, 203, 204, 231,
232, 233, 234 (Profile 2)
• the system skips U-LT, S, and analog loops when selecting
a network connection for synchronization
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Welcome to ISDN / 69
Modular ICS 7.1 Installer Guide