Timing Sources And Timing Distribution - Nortel NTRN10AN Planning Manual

Tributary line timing
Tributary line timing is shown in
When using tributary line timing, a network element derives timing from a
received synchronous tributary signal. This signal is used in network elements
to synchronize the outgoing transport signals in all directions, and the
synchronous tributaries terminated by the network element. Sources of
tributary timing are OC-3, OC-3x4, OC-12, OC-48, DS1, and EC-1 facilities.
When the network element timing mode is set to Line Timing, the primary and
secondary timing references can be provisioned as OC-3, OC-12, OC-48, DS1,
and EC-1 facilities.
Figure 2-49
Flow of synchronization timing signals
NE
Clock
(a) Internal timing
NE
(c) Transport line timing
Legend
= Primary Data flow
= Tributary Data flow

Timing sources and timing distribution

The network elements in an OPTera Metro 3500 system can be integrated into
a synchronization timing architecture. This architecture is a timing reference
hierarchy that allows all network element timing to be referenced to an
accurate common timing source.
Planning and Ordering Guide—Part 1 of 2 NTRN10AN
Operation, administration, and maintenance (OAM) features 2-155
Note: DS1 facilities connected to a DSM module cannot be used as a
timing reference.
Figure 2-49 on page
BITS Stratum-3
or better
VTX-series or
NE
STX Module
(b) External timing
VTX-series or
NE
STX Module
(d) Tributary line timing
= Synchronization Timing
= External Synchronization Reference
Rel 12.1 Standard Iss 1 Apr 2004
2-155, example (d).
EX1513p