Nortel Networks 553-3001-211 manual Automatic clock switching, Clock configurations

Page 344 of 894 NT5D97 Dual-port DTI2/PRI2 card

Automatic clock switching

If the EREF command is selected in LD 60, tracking on the primary or secondary reference clock is automatically switched in the following manner:

•If software is unable to track on the assigned primary reference clock, it switches to the secondary reference clock and sends appropriate DTC maintenance messages.

•If software is unable to track on the assigned secondary reference clock, it switches to free run.

Clock configurations

Clock Controllers can be used in a single or a dual CPU system.

A single CPU system has one Clock Controller card. This card can receive reference clocks from two sources referred to as the primary and secondary sources. These two sources can originate from a PRI2, DTI2, etc. PRI2 cards such as the NT8D72BA are capable of supplying two references of the same clock source. These are known as Ref1 (available at J1) and Ref2 (available at J2) on the NT8D72BA.

The NT5D97 card is capable of supplying two references from each clock source, for example, four references in total. NT5D97 can supply Clk0 and Clk1 from Unit 0 and Clk0 and Clk1 from Unit 1. Either Unit 0 or Unit 1 can originate primary source, as shown in Figure 75 through Figure 78.

There is one Clock Controller cable required for the DDP2 card, which is available in four sizes; this is the NTCG03AA/AB/AC/AD. Refer to “Reference clock cables” on page 323 for more information.

553-3001-211 Standard 2.00 September 2004