Paradyne 336x E1 manual Selecting the Timing Source, Common Clocking Configurations

Operation

Selecting the Timing Source

The E1 NTU provides the ability to select a primary

clock (timing) source that is used to synchronize all of the E1 and data port interfaces on the E1 NTU. The clock for each interface is at the appropriate rate for that interface (e.g., 2.048 Mbps for the E1 interfaces, the configured port rate for the data ports), and it is independent of the primary clock rate. This means that the primary clock rate and the E1 NTU interface rates may be different.

The E1 NTU automatically falls back to the secondary clock when a failure of the selected primary clock is detected. If a secondary clock failure is detected, the E1 NTU falls back to its internal clock.

The clock source configuration options enable you to select either the network interface, a synchronous data port, the internal clock, the G.703 DTE interface, or an external clock. If external clocking is selected, you must use the clock rate configuration option to specify the clock rate. Figure 3-12shows some common clocking configurations. Two sample procedures for configuring timing are given in the following sections, Configuring for Network Timing and Configuring for External Timing. For more information on configuration options, refer to Appendix C.

NOTE

External clock and secondary clock sources are only available for 2-port and 4-port E1 NTUs.

NETWORK

CLOCK: NETWORK CLOCK: NETWORK

CLOCK: INTERNAL CLOCK: NETWORK

CLOCK: EXTERNAL

PBX

CLOCK: DTE (G.703) CONNECTOR

TERMINAL

EQUIPMENT

CLOCK: PORT 1, 2, 3, OR 4

CLOCK: NETWORK

CLOCK: NETWORK

CLOCK: NETWORK

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Figure 3-12. Common Clocking Configurations

3360-A2-GB20-20 December 1996 3-33