Verilink NCC 2020 (880-503284-001) Product Manual Manual de usuario descargar pdf (Pagina 61)

Diagnostics

Verilink NCC 2020 User Manual

-13

With a loopback plug in the network port, any customer equipment

connected to the NCC 2020 (or a data port of any DIU module

assigned to the CSU) should see a loopback condition. If the

customer equipment can report errors, it should indicate that no

errors are being received.

A T1 loopback plug can be made by taking a male RJ-45 connector

and placing two short jumper wires where a cable would normally

go. One jumper is placed from pin one to pin five, the other jumper

connects pin two to pin four. See Figure 5-5 for a drawing of a T1

loopback plug.

NOTE:

When using a T1 loopback plug it may be necessary to

temporarily change the timing selection in the CSU. If the

CSU is set to recover network clock, it will be trying to recover

a clock it is trying to recover, the clock frequency will drift.

For this test, set the CSU clock source to Internal. Remember

to change it back after the test.

Figure 5-5 T1 Loopback Plug

RJ -45

Cable Side

Connector

245

RJ-45 plug held with plastic latching tab unseen at bottom

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Verilink NCC 2020 (880-503284-001) Product Manual Manual de usuario Pagina 61