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A. Configuration Options
A-18
May 2002 8700-A2-GB20-40
Table A-8. System Clock Options
Primary System Clock Reference
Possible Settings (LTU, Model 8777): DSX-1 Port 1, DSX-1 Port 2, DSX-1 Port 3,
DSX-1 Port 4, DSX-1 Port 5, DSX-1 Port 6, DSX-1 Port 7, DSX-1 Port 8, Internal
Default Setting: Internal
Possible Settings (LTU, Model 8779): G.703 Port 1, G.703 Port 2,G.703 Port 3,
G.703 Port 4, G.703 Port 5, G.703 Port 6, G.703 Port 7, G.703 Port 8, Internal
Default Setting: Internal
Possible Settings (NTU): DSL Port 1, DSL Port 2, DSL Port 3, DSL Port 4, DSL Port 5,
DSL Port 6, DSL Port 7, DSL Port 8
Default Setting: DSL Port 1
Determines the source of system timing. Select the most accurate clock available.
DSX-1 Port
n
(Model 8777) – Timing is derived from the specified port. To be a valid clock
source, the port must be enabled and must derive its timing from the DSX-1 network.
NOTE: If the DSX-1 port is configured for Bypass mode, the Primary Clock Source
configuration option on the DSX-1 Interface Options screen must be set to DSX-1, not
Internal (see Tabl e A-4 ). All ports configured as system clock sources must be
traceable to the same clock reference.
G.703 Port
n
(Model 8779) – Timing is derived from the specified port. To be a valid clock
source, the port must be enabled and must derive its timing from the G.703 network.
NOTE: If the G.703 port is configured for Bypass mode, the Primary Clock Source
configuration option on the G.703 Interface Options screen must be set to G.703, not
Internal (see Tabl e A-5 ). All ports configured as system clock sources must be
traceable to the same clock reference.
DSL Port
n
– Timing is derived from the specified port. The port must be enabled and in a
cross-connection.
Internal – Timing is derived from the internal oscillator, which provides a Stratum 4
reference.
Secondary System Clock Reference
Possible Settings (LTU, Model 8777): DSX-1 Port 1, DSX-1 Port 2, DSX-1 Port 3,
DSX-1 Port 4, DSX-1 Port 5, DSX-1 Port 6, DSX-1 Port 7, DSX-1 Port 8, Internal
Default Setting: Internal
Possible Settings (LTU, Model 8779): G.703 Port 1, G.703 Port 2, G.703 Port 3,
G.703 Port 4, G.703 Port 5, G.703 Port 6, G.703 Port 7, G.703 Port 8, Internal
Default Setting: Internal
Possible Settings (NTU): DSL Port 1, DSL Port 2, DSL Port 3, DSL Port 4, DSL Port 5,
DSL Port 6, DSL Port 7, DSL Port 8
Default Setting: DSL Port 1
Determines the source of system timing if the primary system clock source fails. If the
secondary clock source fails, the unit switches to the internal clock.
DSX-1 or G.703 Port
n
– Timing is derived from the specified port. To be a valid clock
source, the port must be enabled and must derive its timing from the DSX-1 or G.703
network.
DSL Port
n
– Timing is derived from the specified port. The port must be enabled.
Internal – Timing is derived from the internal oscillator, which provides a Stratum 4
reference.