92
AR Router
C613-03031-01 REV E
Figure 56: Primary Rate ISDN 120
Ω
loopback plug.
Loopback Plugs for BRI Interfaces
If your router or expansion option’s BRI interface has an MC145474 or
MC145574 transceiver, a loopback plug is required before the BRI interface can
be tested. (Figure 57 on page 93 shows how to wire a suitable loopback plug.)
For all other transceiver types the test can be performed without a loopback
plug. In this case the Test Facility will still perform an internal loopback test,
but this will not test the complete physical interface. To fully test these
interfaces, an external NT mode device is required. Or, if the interface can be
configured for NT mode operation, an external TE device can be used.
To determine which type of transceiver a BRI interface uses, enter the
command:
SHOW BRI TEST
Figure 56-1 on page 92 shows an example of the output screen from the SHOW
BRI TEST command, with the transceiver type listed in the first line.
Figure 56-1: Example output from the SHOW BRI TEST command.
PRI Loopback Plug (RJ45 connector)
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Switch or router
end view
TX+
TX-
RX+
RX-
P120LOOP
Test switches for BRI instance 0 (MC145574 transceiver):
Number Action Status
------------------------------------------------------
1 Transceiver B1 GCI Transp Loop ........... no
2 Transceiver B2 GCI Transp Loop ........... no
3 Transceiver 2B+D GCI Transp Loop ......... no
4 Transceiver B1 GCI Non-Transp Loop ....... no
5 Transceiver B2 GCI Non-Transp Loop ....... no
6 Transceiver B1 S/T Transp Loop ........... no
7 Transceiver B2 S/T Transp Loop ........... no
8 Transceiver B1 S/T Non-Transp Loop ....... no
9 Transceiver B2 S/T Non-Transp Loop ....... no
10 Transceiver External S/T Loop ............ no
11 Transceiver 96kHz Test Tone .............. no
12 Transceiver Force Activation ...... ...... no
13 Transceiver Ignore D Channel Procs ....... no
14 Transceiver Map E Channel to GCI ......... no
15 Transceiver GCI Free Run ................. no
