Control, Transmission, and Synchronization Interfaces
5-34 Issue 8.0 July 2002
Figure 5-21. Example of a Ring Application with
Three Nodes Provisioned Externally Timed
and One Node Provisioned Line Timed (Without
Timing Drops)
In rings with two or more external timing sources (for example, BITS clocks)
available at more than one node, it is recommended to use the backup feature to
provide reliability in the event of a failure. The provisioning modes, which are
labeled in Figure 5-21, demonstrate this concept. Care should always be
exercised to avoid timing loops.
For more information about platform timing modes, refer to "Platform
Synchronization" in this section.
FT-2000
FT-2000
FT-2000
FT-2000
Line Timed
DS3/EC-1/OC-3
P = TIMING IN PRI to TG3-1
S = TIMING IN SECY to TG3-2
BITS
PS
Externally Timed
BITS
PS
BITS
PS
Externally Timed
Externally Timed
Node A
Node B
Node C
Node D
Provisioning Modes:
Node A: External, E Back-up;
Node B: External, W Back-up;
Node C: Line, auto
Node D: External, E Back-up;
E
E
E
E
W
W
W
W
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