Testing
7-4
7612-A2-GB20-10
November 1997
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.
An active DSU loopback initiated from the network disrupts IP data going over the
IMC. However, this test is not disruptive when initiated by the user (via ATI) or by
the NMS.
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:
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.
To initiate a send sequence, select the appropriate Send command. Sending
appears in the Status column followed (after 3 seconds) by Command Complete
at the bottom of the screen.
511 Test Pattern for the Network
This test sends and/or monitors the 511 test pattern over the network interface.
The Monitor 511 test also provides an error counter that can be reset.
To start sending and/or monitoring, select the appropriate Start command.
