Lucent Technologies DDM-2000 OC-3, User & Service Manual

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363-206-285
Technical Specifications
Issue 3 June 2001 10-73
A Markov model was used to calculate the predicted system outage. The model
assumes a mean time to repair of 2 hours for the CO environment and 4 hours for
the RT environment. Individual circuit pack failure rates used in the model were
calculated using the method described in TR-TSY-000332, Issue 4, "
Reliability
Prediction Procedure for Electronic Equipment (RPP)
." A summary of the circuit
pack and fan shelf failure rates is shown in Table and Table 10-32, respectively.
Operation System Interface Availability 1 0
The Telcordia Technologies objective states that the OS outage should be less
than 28 minutes per year (50 percent hardware, 50 percent software).
*
Therefore,
the objective applies to the TBOS and TL1/X.25 interfaces. This objective applies
to circuitry needed to maintain communication from the DDM-2000 OC-3
Multiplexer to the CO's telemetry equipment for access by an OS. Since the OS
interface is used in the CO, the reliability model assumes the mean time to repair
is 2 hours and the environmental factor is 1.0. Table 10-30 lists the predicted
outages for the TBOS and TL1/X.25 interfaces.
Optical Module Maintenance Objective 1 0
According to Telcordia Technologies, the objective for mean time between failure
(MTBF) of a one-way regenerator is a minimum of four years
†
. A regenerator is
defined as any circuit pack that performs the electrical-to-optical and optical-to-
electrical conversion. Table lists the failure rate and MTBFs of the OLIU circuit
packs. All OLIU circuit packs meet Telcordia Technologies objectives.
* TA-NWT-000418, Issue 3, November 1991, p. 36.
† TA-NWT-000418, Issue 3, November 1991, p. 37.