Avaya S8700 Maintenance Manual page 987

For multi-connect configurations

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ATM-SYNC (ATM Synchronization)

Stratum 4 Synchronization

Systems may have primary and secondary synchronization references

(DS1/UDS1 interface circuit packs or ATM-Switch) when using Stratum 4

synchronization.

If the primary synchronization reference in

a valid timing signal, then the flow of system synchronization would travel from the

DS1 interface circuit pack in the EPN to the ATM switch. The primary DS1

interface circuit pack provides a timing signal for the ATM switch clock circuitry.

This synchronization source is then distributed to all of its OC3 Interface Modules.

Each ATM Expansion Interface circuit pack uses the received data stream from

the ATM switch to generate a timing signal. The Tone-Clock circuits in the EPNs

use this signal to generate timing for every circuit pack in their respective EPNs.

All PNs, in the above mentioned scenario are designated the slave port networks.

The ATM switch is the master that contains the system synchronization source. If

the primary synchronization reference does not provide a valid timing signal, ATM

synchronization maintenance infers a switch to the secondary reference.

If the primary synchronization reference is not providing a valid timing signal, the

system automatically switches to the secondary synchronization reference. If the

primary synchronization reference is invalid, and if the secondary reference does

not provide a valid timing signal or is not administered as a synchronization

reference, the switch infers that the local oscillator of the ATM switch provides the

system timing source. If the system is using the local oscillator of the ATM switch

as the system timing source because the primary and secondary references are

providing invalid timing signals, when either the primary or secondary reference

becomes valid again, the system switches back to the primary or secondary

source. When both the primary and secondary source become valid, the system

switches to the primary source, since the primary source is always preferred over

the secondary source when both sources are equally healthy.

Figure 8-10 on page 8-266

synchronization reference into the ATM switch.

Figure 8-10 on page 8-266

depicts a simplex ATM PNC with T1/OC3

is providing

Issue 1 May 2002

Troubleshooting