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Transmission and Synchronization Interfaces
5-42 Issue 3 June 2001
Sending DS1 AIS on the output of the BBF2B/BBF4 circuit pack can be
provisioned by using the set-sync command. Depending on the quality level of
the incoming sync messages, this new parameter can be provisioned to send DS1
AIS upon receiving level 5 (default), level 4, level 3, or level 2. Refer to Table 5-3
and Table 5-4 for definitions of quality levels. AIS will be sent as long as the
received message is at the provisioned or greater in quality level number.
Examples 5
In this part, some detailed examples are given to show specifically how the
synchronization messages propagate through the DDM-2000 OC-3 network and
assist in the recovery from a fiber failure. Through these examples, one can
extend the same concept to any other network that may include different
topologies, number of sites, failure locations, and number of BITS clocks.
NOTE:
All nodes in a ring using automatic synchronization reconfiguration must
have the synchronization messaging and automatic synchronization
reconfiguration features enabled to prevent alarms.
In all of the following examples, if the sync message parameter within the
set-oc3 command has been provisioned to “S byte” for an optical interface, then
the equivalent quality level S byte message will be transmitted from that optical
interface. The following are equivalent messages:
K2: Sync Quality Unknown is the same as, S1: Sync Trace Unknown
K2: Timing Looped Back is the same as, S1: Don’t Use
K2: Internal Clock is the same as, S1: Traceable SONET minimum Clock
K2: Stratum 3 is the same as, S1: Traceable Stratum 3.
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