System Management
7210 SAS M, X Basic System Configuration Guide Page 165
Synchronization Status Messages (SSM)
SSM provides a mechanism to allow the synchronization distribution network to both determine
the quality level of the clock sourcing a given synchronisation trail and to allow a network element
to select the best of multiple input synchronization trails. Synchronization Status messages have
been defined for various transport protocols including SONET/SDH, T1/E1, and Synchronous
Ethernet, for interaction with office clocks, such as BITS or SSUs and embedded network element
clocks.
SSM allows equipment to autonomously provision and reconfigure (by reference switching) their
synchronization references, while helping to avoid the creation of timing loops. These messages
are particularly useful to allow synchronization reconfigurations when timing is distributed in both
directions around a ring.