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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Loss of System Clock Transitions
Each peripheral card incorporates transition-loss detectors, which monitor the internal
clock signals from each core. Failure of the clock is defined as a loss-of clock
transitions for a period exceeding a nominal threshold of 125-500ns. There is no
further persistency check on clock failures.
Failure of Alignment
If the alignment bits contained within the diagnostic messages are incorrect, the
detecting destination port generates a loss-of-frame alarm. This check is subject to the
persistence check (refer to Persistence Check of Diagnostic Message Failure) and
protection switching is in accordance with the priorities in Section 7.5.3. You may
enable/disable this check.
Demand by the Multiplexer Controller
A request to switch is issued to all destination ports on receipt of a core-failure
indication by the Multiplexer Controller. You may issue a request via the NMI. These
requests are treated as core-failure conditions. No persistence check is carried out on
such conditions.
Persistence Check of Diagnostic Message Failure
In cases of diagnostic message failure, a persistence is performed to prevent spurious
switching during transient conditions (e.g. MSP switching). This check takes the form
of a threshold on the number of permissible consecutive mismatches of the diagnostic
messages. A hardware persistence is applied independently to each VC. You can set
this persistence between 1-- 256 successive failures of the check for VC 3/4, and 1 - 7
for VC 1/2. The value is global for all VC 1/2s and VC 3/4.
7.7.4
Further Protection Switching Criteria
In general, the criteria for initiating core card protection switching are the same as for
SMA switch card protection. These specify forced switching under operator control
and automatic switching actioned by peripheral traffic cards, either by themselves, or
on instruction from the CCU controller. The latter is based on the Switch Diagnostics
Messaging (SDM) scheme.
The same failure criteria for core card protection is detected by both the system’s
peripheral traffic cards and the core cards’ own traffic modules, namely the SDH line
interface modules and the core tributary card modules. These line modules/tributary
modules monitor for failures on both their parent core card and the protection partner
core card.
