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10-4
Cisco ONS 15454 Reference Manual, R8.5.x
78-18106-01
Chapter 10 Timing
10.3.1 SONET SSM Messages
10.3.1 SONET SSM Messages
SSM messages are either Generation 1 or Generation 2. Generation 1 is the first and most widely
deployed SSM message set. Generation 2 is a newer version. If you enable SONET SSM for the
ONS 15454, consult your timing reference documentation to determine which message set to use.
Table 10-1 and Table 10-2 show the SONET Generation 1 and Generation 2 message sets.
10.3.2 SDH SSM Messages
If you enable SDH SSM for the ONS 15454, consult your timing reference documentation to determine
which message set to use. Table 10-3 shows the SDH SSM messages.
Table 10-1 SONET SSM Generation 1 Message Set
Message Quality Description
PRS 1 Primary reference source—Stratum 1
STU 2 Synchronization traceability unknown
ST2 3 Stratum 2
ST3 4 Stratum 3
SMC 5 SONET minimum clock
ST4 6 Stratum 4
DUS 7 Do not use for timing synchronization
RES — Reserved; quality level set by user
Table 10-2 SONET SSM Generation 2 Message Set
Message Quality Description
PRS 1 Primary reference source—Stratum 1
STU 2 Synchronization traceability unknown
ST2 3 Stratum 2
TNC 4 Transit node clock
ST3E 5 Stratum 3E
ST3 6 Stratum 3
SMC 7 SONET minimum clock
ST4 8 Stratum 4
DUS 9 Do not use for timing synchronization
RES — Reserved; quality level set by user
Table 10-3 SDH SSM Messages
Message Quality Description
G811 1 Primary reference clock
STU 2 Sync traceability unknown