MIL-HDBK-2051 Fiber Optic Shipboard Cable Topology Design GuidanceThis handbook contains suggested design rules for defining a fiber optic cable topology. In addition, this document describes a suggested approach for developing and designing a fiber optic cable topology FOCT for a Naval platform and also identifies the applicable fiber optic component specifications. This handbook is primarily intended for use by the fiber optic cable topology design engineer, but provides useful information to a system design engineer as well.

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MIL-HDBK-2051(SH)

a. General spare fibers (see 3.2.21)

b. Growth fibers for future systems (as yet unidentified)

Unallocated fibers provide shipboard flexibility in recovering from random failures and battle damage, and can improve survivability and availability. In addition, when new systems or upgrades are installed on a ship already in service, some or all of the required trunk fibers may already be installed which facilitates a smoother ship upgrade process.

5.3.1.1.1.4   Unused.  Unused fibers are fibers that are not required in the design, but occur within the FOCT when the required number of fibers is less than the number of fiber available within a standard cable size.

5.3.1.1.2   Local fiber categories  .   There are also four categories of local fibers:

a. Allocated and used

b. Allocated and not used

c. Unallocated

d. Unused

5.3.1.1.2.1   Allocated and used (local)  .  Allocated and used fibers are the fibers required by the system to interconnect the system equipments together

via the FOCP fibers.  Fibers contained within this category are:

a. Normal channel fibers (see 3.2.11)

b. Alternate channel fibers (see 3.2.3)

c. NRC fibers (see 3.2.10)

5.3.1.1.2.2   Allocated and not used (local)  .  Allocated and not used fibers are system required fibers that are not actively used by the end user

equipment.  Manual reconfiguration is required at the end user equipment and in the interconnection box to activate use of these fibers.  Fibers contained within this category are:

a. System required spares

b. System required redundant fibers

c. System required growth fibers

5.3.1.1.2.3   Unallocated (local) .  These are required spare fibers for local cables which penetrate water tight bulkheads.

5.3.1.1.2.4   Unused (local) .  Unused fibers are fibers that are not required by the end user equipment, but occur within the FOCT when the required number of fibers is less than the number of fiber available within a standard cable size.

5.3.1.2   Trunk fiber quantity allocation  .  The number of required fibers in a trunk(s) between interconnection boxes is determined from the number of

fibers required by all of the systems for each of the categories listed in

5.3.1.1.  The number of trunks is affected by system routing restrictions (see

5.3.1.6 and 5.4.1.1).

5.3.1.2.1   Quantity of allocated and used fibers (trunk)   .  The number of allocated and used trunk fibers is determined from the end user equipment drawings and ship configuration drawing.  If possible, fiber for systems that are planned for installation, but not installed prior to delivery, should be included in this category.

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