Symmetricom 1100, 1000 manual Input SSMs, Output SSMs

Chapter 1 Overview of the TimeProvider

Synchronization Status Messages (SSMs)

Table 1-4. ANSI SSM Quality Level Definitions (Continued)

Description	Quality Level	Abbreviation
SONET Minimum Clock traceable	7	SMC
(20 ppm clock)
Stratum 4 traceable (32 ppm clock)	8	ST4
Do Not Use for synchronization	9	DUS
Table 1-5. ITU SSM Quality Level Definitions
Description	Quality Level	Abbreviation
Synchronized – Traceability Unknown	0	UNK
Primary Reference Clock	2	PRC
Transit Node	4	SSUT
Local Node	8	SSUL
Synchronization Equipment Clock	11	SEC
Do Not Use for synchronization	15	DNU

The TimeProvider handles SSMs in accordance with T1X1.3 TR33, T1.101-1999, GR-253, and GR-378.

Input SSMs

The TimeProvider extracts and decodes the SSM (if present) on the available inputs. Using this information, the TimeProvider can automatically select the input with the higher quality level.

You can manually provision the input quality level for those signals that do not have SSM information or you can provision INP1 and INP2 to read the SSM on the input; in either case the quality level of the reference input becomes the system’s quality level, which is passed through to the outputs in the output SSM. If the IOC enters the Free-run or Holdover mode, the system’s quality level is determined by the CLKTYPE parameter for the local oscillator on the selected IOC module. You can provision the CLKTYPE parameter to Type I, Type II, ST2, or ST3E.

Output SSMs

You must provision the TimeProvider’s outputs according to the type of SSM operation you are using:

For ANSI SSM operation, set the output type to Extended SuperFrame (ESF) for ANSI SSM operation.

For ITU SSM operation, set the output type to Channel Associated Signaling (CAS) or Common Channel Signaling (CCS) with CRC4 framing. The SSM bit location can be set by the user.

42 TimeProvider User’s Guide 097-58001-02 Revision G – April 2008