Marconi OMS 1200
Technical Product Description
221 02-ZAP 701 25/1 Rev C 2006-08-04
© Ericsson AB 2006
03PHB00004AAV-CUA
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7.9.1.2
Mode of Operation OMS 1260 Only
The OMS 1260 is able to operate with the following numbers of protected PDH
channels shown in Table 7-17.
Table 7-17: Protected PDH Channels
PDH Rate
OMS 1260
2M
Up to 126 ports
34/45M 10
ports
140M
3 ports
Note:
The above are maximum figures for single bit rates.
7.9.1.3
Wait to Restore and Do Not Revert
Either a Wait-to-Restore (WTR) or Do-not Revert state is entered when a working port
recovers from a failure.
In revertive mode of operation, the wait-to-restore state is automatically entered when
a worker port recovers from a failure. Entry to the wait-to-restore is inhibited if a higher
priority condition exists when the working port recovers.
When the wait-to-restore state is entered, a timer is set. The condition is de-activated
upon expiry of the timer period. The condition is also de-activated if a higher priority
condition is received during the timer period.
You may configure the timer from 0 to 30 minutes in one-minute (+/- 5 second) steps.
You can configure the WTR period globally and on an individual port basis for
protected ports. The default value is 10 minutes.
Note:
You arel only able to retrieve WTR values from the NE on an individual port
basis.
The Do-not Revert state is entered under the same circumstances as WTR. However,
there is no associated timer. This state remains active until a higher-level condition is
received, at which point the Do-not Revert is reset. If it is active, it is immediately reset
by a re-configuration into revertive mode.
7.9.2
Protection Switching Criteria
7.9.2.1 Failure
Detection
Two criteria are used to indicate the status of the two protected PDH ports to the
protection switching control mechanism. The interface cards generate these flags and
the switch unit receives them and uses them to trigger the next stage of the protection
switching sequence.
A failure indication is raised if one, or more, of the following criteria is detected:
1
Loss of Tributary input.
2
Loss of Frame Alignment.
3
Receipt of AIS.