Lucent Technologies 7820-0802-003 Configuring clocking, Configuring the front-end transceiver

Configuring T1 Cards

Configuring clocking

Configuring clocking

You can configure the TAOS unit to use any of the T1 lines as a master phase-locked loop (PLL) clock source for synchronous connections for an entire system. In synchronous transmission, both the sending device and the receiving device must maintain synchronization to determine where one block of data ends and the next begins.

From the T1 lines configured as eligible clock sources, the TAOS unit chooses a clock source on the basis of priority. If multiple T1 lines are configured as eligible clock sources and have an equal clock priority, the TAOS unit chooses one of them at random. Once chosen as the clock source, the line used until it becomes unavailable or a higher-priority source becomes available.

If no eligible external sources are available, the system uses an internal clock generated from the primary shelf controller. Using the internal clock is generally not recommended.

The Clock-Source diagnostic command displays the current master clock source and any available clock source. Sources from layer 2 up, which are preferred, are marked with an asterisk.

To specify a clock source and set a priority, proceed as follows after reading in the line’s T1 profile:

admin> set clock-source = eligible

admin> set clock-priority = high-priority

admin> write

Configuring the front-end transceiver

The front-end type of the T1 transceiver can be CSU or DSX.

If you are connecting the TAOS unit to a DSX, set the Front-End-Type to DSX. With this setting you must also specify the length of the physical T1 line in feet. The value must reflect the longest line length you expect to encounter in your installation, up to a maximum of 655 feet (200m).

If you are not connecting the TAOS unit to a DSX, set Front-End-Type to CSU. You might also have to set a line buildout value to specify the amount of attenuation, in decibels, that the TAOS unit must apply to the line. If the TAOS unit is too close to a repeater, you need to add some attenuation to reduce the strength of the signal. Ask your service provider whether you need attenuation and, if so, how much.

To specify DSX settings, proceed as in the following example after reading in the line’s T1 profile:

admin> set front-end-type = dsx admin> set dsx-line-length = 1-133

admin> write

APX 8000/MAX TNT/DSLTNT Physical Interface Configuration Guide 7-17