Nortel Passport 15000 Preparation Manual page 46

46 Chapter 2 Planning considerations
241-1501-205 5.2S2
Each fiber shelf includes two latched drawers that accommodate up to 20 fiber
cables. Up to six fiber units can fit into either the front or the rear of a NEBS
2000 frame that has a switch in its lower half. The fiber units can be mounted
at both the front and the rear of the frame. When installing them at the rear,
the cable path from the FP faceplates may not be practical.
The couplers that are part of fiber optical Y-splitter cable assemblies (for
example, for NTHW44 FPs) must not reside inside the NTHW50 when
managing cable slack from the FPs. The presence of a coupler inside a unit
increases the risk of losing traffic because the space to add or remove cables
will be more confined and congested.
All fiber units must have separate mounting holes except when shared with a
cable management bracket.
A switch fully provisioned with only 4-port OC-3s would require three fiber
management units, that is:
14 FPs x 8 connections per FP = 112 cables
112 divided by 40 = 2.8, which means three 2-drawer fiber units
Based on the number of fiber ports your configuration will initially have or
might expand to, determine how many fiber units you will need. Then
consider where to locate the fiber units relative to the location of the switch.
Wherever you plan to locate the fiber management unit, ensure that it does not
constrict the access of the fiber cables into it, or unavoidably exceed the bend
radius limitations.
Note 1: Once at least one fiber management unit is installed in the upper
half of a NEBS 2000 frame, adding a second switch to that frame would
require relocating the fiber unit. Relocation means removing the fiber
optical connections from service at both ends of the cable path, and
disconnecting one end to remove the cables from the fiber unit. Consider
installing the fiber management unit in a 21-inch (53.34-cm) mounting
apparatus that is anchored near the switch.
Note 2: Nortel Networks recommends that a fiber management unit not
be installed in a 23-inch (58.42-cm) EIA rack that already houses a
Passport 15000 or 20000 switch because of weight limitations.