Testing
7-3
7610-A2-GB20-00
November 1996
CSU or External Network Loopback
CSU loopback is an external loopback that is located as close as possible to the
network interface. An active CSU loopback disrupts IP data going over the IMC.
DSU
CSU
DTE
Interface
Aggregate
DTE
Port
DDS
Network
Port
496-15144
CSU Loopback
DSU or Internal Network Loopback
DSU loopback is an internal loopback that is located as close 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:
In-band V.54 Up (activation) code to request a Remote DSU Loopback
(V.54 Loop 2) at the remote DSU or
In-band V.54 Down (deactivation) code to request the termination of a
Remote DSU Loopback (V.54 Loop 2) at the remote DSU
Refer to the
Network Tests
section for an example of the Network Tests screen.
Select Send. Sending appears in the Status column followed (after 3 seconds) by
Command Complete at the bottom of the screen.
