G.709 ODU Maintenance Signals

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ODU maintenance signals 

Three ODU maintenance signals are defined as per G.709: ODU-AIS, ODU-OCI and ODU-LCK

ODU alarm indication signal (ODU-AIS) 

 ODUK-AIS-PM is a secondary condition that indicates a more serious condition such as the LOS (OCN/STMN) alarm occurring downstream. The ODUK-AIS-PM condition is reported in the path monitoring area of the optical data unit wrapper overhead. ODUK-AIS-PM is caused by the upstream ODUK-OCI-PM. 

ODUk-AIS is specified as all "1"s in the entire ODU signal, excluding the frame alignment overhead (FA OH), OTU overhead (OTU OH) 

The ODUk contains one instance of ODU AIS. The ODUCn contains n instances of ODU AIS, numbered 1 to n (ODU AIS #1 to #n).

In addition, the ODU-AIS signal may be extended with one or more levels of ODU tandem connection, GCC1, GCC2, EXP and/or APS/PCC overhead before it is presented at the OTN interface. This is dependent on the functionality between the ODU-AIS insertion point and the OTN interface.

The presence of the ODU-AIS is detected by monitoring the ODU STAT bits in the PM and TCMi overhead fields.

 

ODUk open connection indication (ODUk-OCI) 

It indicates that the upstream signal is not connected to a trail termination source. The error is read as a STAT bit in the path monitoring area of the digital wrapper overhead. ODUK-OCI-PM causes a downstream ODUK-LCK-PM alarm. 

ODUk-OCI is specified as a repeating "0110 0110" pattern in the entire ODUk signal, excluding the frame alignment overhead (FA OH) and OTUk overhead (OTUk OH) (see Figure 16-4).

NOTE – ODUCn OCI is not defined.

NOTE – The repeating "0110 0110" pattern is the default pattern; other patterns are also allowed as long as

the STAT bits in the PM and TCMi overhead fields are set to "110".

In addition, the ODUk-OCI signal may be extended with one or more levels of ODUk tandem connection, GCC1, GCC2, EXP and/or APS/PCC overhead before it is presented at the OTM interface. This is dependent on the functionality between the ODUk-OCI insertion point and the OTM interface.

The presence of ODUk-OCI is detected by monitoring the ODUk STAT bits in the PM and TCMi overhead fields. 

 

ODU locked (ODU-LCK)

 ODUK-LCK-PM indicates that a signal is being sent downstream to indicate that the upstream connection is locked, preventing the signal from being passed. The lock is indicated by the STAT bit in the path overhead monitoring fields of the optical transport unit overhead of the digital wrapper. 

ODU-LCK is specified as a repeating "0101 0101" pattern in the entire ODU signal, excluding the frame alignment overhead (FA OH) and OTU overhead (OTU OH) (see Figure 16-5).

ODU-LCK
NOTE – The repeating "0101 0101" pattern is the default pattern; other patterns are also allowed as long as

the STAT bits in the PM and TCMi overhead fields are set to "101".

In addition, the ODU-LCK signal may be extended with one or more additional levels of ODU tandem connection, GCC1, GCC2, EXP and/or the APS/PCC overhead before it is presented at the OTN interface. This is dependent on the functionality between the ODU-LCK insertion point and the OTN interface.

The presence of ODU-LCK is detected by monitoring the ODU STAT bits in the PM and TCMi overhead fields.

 

 

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