Avaya 6402D Guia Do Utilizador

This chapter illustrates the design process for a hypothetical main distribution frame (MDF) using a

seven-module system. The process consists of two steps: sizing the MDF and constructing the MDF.

Sizing is the determination of the number of 300-pair terminal blocks needed to construct the MDF.
First, the requirements of the four principle fields are assessed.  Second, the number of blocks needed
for each field to meet those requirements is determined.

The four principal fields on the MDF are the central office (CO) trunks of network services, auxiliary

and miscellaneous, equipment ports, and distribution fields. The following are the requirements for each
field.

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The network services field, which uses green labels, is where the CO cables terminate. For this

installation all trunks are digital.  There is a direct connection between the customer’s channel
service unit (CSU) and the digital service level-1 (DS1) interface of the telephone company. No
cables have to be terminated on this field, which eliminates the need for terminal blocks.

●    

The auxiliary and miscellaneous field, which uses yellow labels, is where the cables from the

auxiliary equipment terminate. Two auxiliary cabinets, whose contents are unknown, serve this
system. Allow for the termination of twelve 25-pair cables from each cabinet.

In addition, a maximum of twelve 25-pair cables from the common control (CC) cabinet terminate
on this field. This includes the cabling for one attendant console.

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The equipment port field, which uses purple labels, is where the cable from the equipment ports

terminate. There are 57 port carriers in the system and ten DS1/MFAT carriers used to hold ANN15
remote group interface (RGI) circuit packs. Modules 00 and 02 contain only six port carriers each.
The remaining five modules contain nine port carriers and two DS1/MFAT carriers each.

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The distribution field, which uses white labels, is where the distribution cables that run to the
intermediate distribution frames (IDFs) terminate.

Numerous factors affect the sizing of the

distribution cable, including the stations served by closets, the number and type of stations, the
spares needed, and the possibility of cable breakage.

Allow for the termination of 14,000

distribution cable pairs.