Sparing information

Overview

This section provides guidelines and a procedure to determine the number of spares needed at each location.

Important!

The number of spares for each code must be determined and maintained separately, based on the in-service population of the code at each location.

Lead time

Lead time, or turnaround time is the elapsed time between a known FRU failure at a given service location and the arrival of a repaired (or new) FRU at the location where spare circuit packs are stocked to maintain a spare FRU level consistent with the population in service.

Lead time should not be confused with mean time to repair, which is the elapsed time between discovery of the failure of an in-service FRU and when a replacement is put into service.

Sparing graph for 10-day lead time

Use the graph below to plan the number of spares necessary for the circuit packs and equipment used in Alcatel-Lucent 1665 DMX.

Figure 7-1: Sparing graph for a 10-day lead time

Using the sparing graph

Use the following procedure to determine how many spare circuit packs, PTMs, or other pieces of equipment are required for each code at each location to maintain 99.9% service continuity, given a 10-day lead time.

1. Locate the failure rate for the unit under consideration using the tables above.

2. See Figure 7-1, Sparing graph for a 10-day lead time and select the curve that represents the nearest failure rate. Interpolation may be necessary.

3. Follow the curve until it intersects the vertical line that represents the number of units in service at the given location. Interpolation may be necessary.

4. Refer to the horizontal line immediately above the intersection. The number associated with this line is the minimum number of spares recommended for that location.

5. Repeat Steps 1–4 for each circuit pack, PTM, and piece of equipment.

Example of using the graph

If there are 100 LNW49 OC-12 OLIUs (failure rate of 4523) in service at a given Central Office location and your lead time is 10 days, then you should order and stock 3 spare LNW49 circuit packs for that location.