363-206-305
Technical Specifications
Issue 3 June 2000
10-59
DDM-2000 FiberReach Multiplexer Reliability
10
Summary
10
This section describes the Telcordia Technologies reliability requirements that
apply to the DDM-2000 FiberReach Multiplexer and the calculations used to
predict how the DDM-2000 FiberReach Multiplexer meets those standards.
The DDM-2000 FiberReach Multiplexer meets all the applicable Telcordia
Technologies reliability requirements that cover transmission availability, operation
system (OS) availability, optical module maintenance, and infant mortality. A
summary of the reliability predictions and requirements is shown in Table 10-26
and Table 10-27. The applicable Telcordia Technologies requirements and
objectives were clarified through interactions with Telcordia Technologies during
their audit of the DDM-2000 OC-3 Multiplexer. The basis for these requirements
comes from TA-TSY-000418,
Generic Reliability Assurance Requirements for
Fiber Optic Transport Systems
. The method and assumptions used to calculate
DDM-2000 FiberReach Multiplexer reliability predictions are described in the
following paragraphs. Each paragraph is devoted to one of the reliability
parameters which must meet a Telcordia Technologies requirement or objective.
Transmission Availability
10
Telcordia Technologies
requirements
state that the probability of a hardware
caused outage on a two-way channel within a SONET multiplexer should be less
than 1.75 minutes per year in a central office environment
*
and 5.25 minutes per
year in a remote terminal environment.
†
Telcordia Technologies
objectives
for
outages are 0.25 minutes per year for the central office
‡
and 0.75 minutes per
year for remote terminal environments.
§
The outage requirements and objectives apply to any part of the product needed
to process an incoming high-speed or low-speed signal (DS1 to OC-1 or OC-1 to
DS1). An outage is defined, for this and all other outage requirements, as any 1-
second interval with a bit error rate of 10
-3
or worse.
¶
The predicted hardware
outages for various configurations of the system are given in Table 10-27.
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
* TA-NWT-000418, Issue 3, November 1991, p. 17.
† TA-NWT-000418, Issue 3, November 1991, p. 28.
‡ TA-NWT-000418, Issue 3, November 1991, p. 18.
§ TA-NWT-000418, Issue 3, November 1991, p. 28.
¶ TR-TSY-000009, Issue 1, May 1986, p. 4-11.
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