Lucent Technologies DDM-2000 OC-3 User Manual

363-206-285
Technical Specifications
Issue 3 June 2001
10-47
Plug-In Maintenance Sparing Guidelines 10
Table 10-20 provides a guideline for determining the number of DDM-2000 OC-3
plug-in spares needed for a given number of plug-ins in the field. The sparing
guide serves as an initial estimate and is calculated with the following
assumptions:
■ The method for calculating spares follows the procedure described in
Telcordia Technologies TR-TSY-000385, Issue 1.
■ The steady-state failure rate is assumed. Failure rates are based on the
reliability prediction procedure (RPP) method described in TR-TSY-
000332, Issue 4.
■ The spare availability objective (SAO) is 99 percent. The SAO is the long-
term probability that a spare plug-in is available when it is needed.
■ A no-trouble-found (NTF) factor of 1.67 is multiplied to the failure rate. This
accounts for replacements of plug-ins when actually no failure has
occurred. The NTF factor is expected to approach 1.25 as the product
matures. The likelihood of an NTF decreases as the product matures, and
sparing needs will therefore diminish over time.
■ Turnaround time of a returned plug-in is two weeks.

Lucent Technologies DDM-2000 OC-3 Specifications

General

Brand	Lucent Technologies
Model	DDM-2000 OC-3
Category	Multiplexer
Language	English