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Testing
5-5
7520-A2-GB20-20 May 1998
DSU or Internal Network Loopback
DSU loopback is an internal loopback that is located as closely as possible to the
customer interface serving the DTE.
"
Procedure
To run a DSU loopback:
1. Position the cursor at the Start command next to DSU Loopback on the
Network Tests screen.
2. Press Enter.
3. The Start command is changed to Stop. If you want to manually stop the test,
verify that the cursor is positioned at the Stop command.
4. Press Enter. The duration of the test is displayed.
DSU CSU
DTE
Interface
Aggregate
DTE
Port
DDS
Network
Port
496-15160
DSU Loopback
Send V.54 Up/Down Sequences
The local DSU can send an ITU-T V.54 Up or Down sequence to request the
activation or termination of a DSU (digital) loopback of a remote unit. This is the
same as the DSU Loopback shown above except the test is activated remotely.
The DSU can send an:
H
In-band V.54 Up (activation) code to request a Remote DSU Loopback
(V.54 Loop 2) at the remote DSU, or
H
In-band V.54 Down (deactivation) code to request the termination of a
Remote DSU Loopback (V.54 Loop 2) at the remote DSU.
"
Procedure
To start or stop a remote DSU loopback:
1. Position the cursor at the Send command next to Send V.54 Up or Send V.54
Down on the Network Tests screen.
2. Press Enter.
Sending appears in the Status column followed (after a few seconds) by
Command Complete at the bottom of the screen.
Refer to Running Network Tests on page 5-3 for an example of the Network
Tests screen.