Digital Trunk Clocking - NEC SL2100 Features And Specifications Manual

ISSUE 1.0
Description
The SL2100 CPU has a built-in clock source for all digital trunk units. Digital trunk units are connected
via an internal PLO (Phase Locked Oscillator) to derive Primary Clock from the network in priority
order. If priority is set up incorrectly, or if two primary clocks are coming in, slips may occur causing
improper data synchronization. The Phase Locked Oscillator (PLO) equipped with the SL2100 CPU is
the timing source for all digital trunk units in the system. The PLO synchronizes the system and clocks
signals from another office. When the SL2100 is a clock receiver office, the PLO generates the clock
signal according to the source clock signals received from the source office within the network. The
source clock signals are extracted from digital trunk units and are supplied to the PLO.
The PLO synchronization source priorities are as follows:
1. 1PRIDB-C1
2. 2BRIDB-C1
3. IP7[ ]-CPU-C1
Conditions
• If multiple PRIs exist, the system chooses the first one that synchronized with the carrier.
• If there are multiple PRIs and the one being used for the source goes down, the system begins to
count forward in slot numbers looking for the next available PRI.
• If multiple BRIs exist and no 1PRIDB-C1 exists, the SL2100 CPU chooses the first BRI that
synchronized with the carrier.
• If there is one 1PRIDB-C1 and the one being used for the source goes down, the SL2100 CPU
looks to see if there are any BRIs installed in the system. If there are no BRIs, the SL2100 CPU
becomes the new synchronization source. The reason for this is when a 1PRIDB-C1 is installed in
the system.
Default Settings
None
System Availability
Terminals
None
Required Component(s)
CPU
2BRIDB-C1 - OR - 1PRIDB-C1
Related Features
ISDN Compatibility
Features and Specifications Manual

Digital Trunk Clocking

SL2100
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1-245