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A-16
8700-A2-GB20-00April 2000
Table A-8. System Clock Options
Primary System Clock Reference
Possible Settings (LTU, Models 8747, 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, Internal
Default Setting: Internal
Determines the source of system timing. Select the most accurate clock available.
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 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, Models 8747, 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, Internal
Default Setting: Internal
Determines the source of system timing if the primary system clock source fails. If the
secondary clock source fails, the unit switches to secondary holdover mode.
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 and in
a cross-connection.
Internal – Timing is derived from the internal oscillator, which provides a Stratum 4
reference.