Network Router User Manual

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10-10 DCP Mode 1 Installation and Administration

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Performing Loopback Test

AT&T Network Systems requires loopback capabilities in order to test and support AUDIX networking

over switched digital services (SDS).

NOTE

The AUDIX networking ports will be unavailable for the duration of the loopback test.

Therefore, the test should not be conducted during prime-time hours.

In order to conduct a loopback test, you must have installed the loopback MPDM/M1*. One MPDM/M1*

is required per customer location, not per AUDIX system. (The MPDM/M1* must have the V.35 interface

described earlier in this chapter.) You will also need to disconnect the AUDIX Networking Breakout Cable

(H600-331, Group 2) from the AUDIX system for the duration of the test, so the system will have no

networking capabilities during the test. See Figure 10-6, Loopback Test with the H600-331, Group 2

Cable. (If you are using the H600-331, Group 1 cable, you will only need to use one of the DCP lines. See

Figure 10-7, Loopback Test with the H600-331, Group 1 Cable.)

When a loopback test is to be conducted, complete the following steps:

1. Busy out the AUDIX networking ports as follows:

a. If the RS-232 ports are converted to DCP using an MPDM/M1*, set the

SELFTEST/NORMAL switch on the MPDM to SELFTEST.

b. Use the maintenance : network form to busy out all of the AUDIX networking ports.

2. Connect the loopback MPDM/M1* (with the V.35 interface card) as follows:

• If you are using the H600-331, Group 2 Cable, do one of the following:

— If a 356A adapter is available (see Figure 10-6, Loopback Test with the H600-331, Group 2

Cable), disconnect the Amphenol 50-pin male connector from the ACC D05 port on the

AUDIX system. Connect the Amphenol connector to the 25-pair male connector 356A

adapter using a 50-pin female-to-female Amphenol adapter. Plug one end of the D8W-87

cord into slot 1 of the 356A adapter, and the other end into the MPDM/M1* data module.

This makes DCP channels 1 and 2 available for the loopback test.

— If a 356A adapter is not available, patch a 103A adapter to the DCP interface for the ﬁrst

physical port (ELL) at the cross-connect ﬁeld. Plug one end of the D8W-87 cord into the

103A adapter, and the other end into the MPDM/M1* data module. This makes DCP

channels 1 and 2 available for the loopback test.

• If you are using the H600-331, Group 1 Cable, borrow one of the AUDIX DCP ports as shown in

Figure 10-7, Loopback Test with the H600-331, Group 1 Cable.

3. Put the loopback MPDM/M1* (with the V.35 interface) into normal mode.

4. Have Network Systems conduct the loopback test on the port connected to the loopback

MPDM/M1*. Once the MPDM/M1* answers the call, put it into remote loopback mode.

5. When the test is completed, have Network Systems disconnect the call or press the

ORIGINATE/DISCONNECT switch on the loopback MPDM.

6. Connect the network breakout cable (H600-331, Group 1 or Group 2) back to the AUDIX system as

before the test.