Operating the DSU
Test Branch
The Test branch provides extensive testing capabilities for the DSU, the DDS circuit, the DBM (if installed), and the backup circuit. When the tributary DSU receives a test request from the control DSU, it aborts any locally initiated test in progress.
Running a test can affect your application data or may cause your application session to be dropped depending upon
Abort
The Abort selection allows you to abort a test that is running. The DSU cannot run any other test until the test in progress is aborted.
There are two types of selections to abort a test:
•Selective terminates whatever test is in progress at the local DSU.
•Subn (Subnetwork) only displays at the control DSU. This selection terminates any test running at the control DSU or at a tributary DSU or DBM associated with the control.
After selecting either Selective or Subn, the test is terminated and the DCP displays the message Command Complete.
Device Test
The Device (Devic) Test uses a test pattern generator built into the DSU. If a DBM is installed, the DBM must be in Idle mode, with no call in progress if you want to run a Device Test.
NOTE
On
Loopback
The Loopback (Lpbk) branch displays four loopbacks:
•Local Loopback (LL)
•DTE Loopback (DTE)
•Digital Loopback (DL)
•Remote Digital Loopback (RL)
Figure 4-3 shows where each loopback occurs on the circuit. Refer to the figure as you read about loopbacks.
Local Loopback
Local Loopback (LL) is
While the DSU is in Local Loopback, any data transmission by the DTE is returned as received data. An operator can send a test pattern and verify correct reception of the test. The DSU does not monitor this testing.
Figure 4-3. Loopbacks
December 1996 |
