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Operating the DSU
4-93615-A2-GB20-20 December 1996
Manual Backup
You can control each step of a backup attempt by
following one of these procedures.
Placing a Backup Call
To
place a backup call:
. Procedure
1. Go to the Bkup option set under the Confg branch
and set
Auto Bckup
to Disab.
2.
Select
Bckup
(Backup branch) to select a
telephone number from the Backup Directory.
3.
Select
Dial, the
Backup Dir
screen is displayed
identifying the Backup Directory indicator.
If the telephone number in the Backup Dir
ectory is
the number you want to dial, go to Step 5.
4. Select another telephone number to call:
• Press the F1 key (↑) to increment the directory
indicator (e.g., 1 to 2).
• Press the F2 key (↓) to decrement the indicator
(e.g., 2 to 1).
5.
Select
Dial
(F2); the DBM places the call.
6.
Once the dialed call has been established, select
!Cnnct
to switch data to the dialed connection.
Manual Dial Backup Termination
• If
in Standby mode, select
Disc.
•
If in Dial Backup mode, select
DrBU.
Test Branch
The Test
branch provides extensive testing capabilities
for the DSU, the DDS circuit, the DBM, and the backup
circuit. Most tests can be run simultaneously on the DSU
and DBM. When the tributary DSU receives a test request
from the control DSU, it aborts any locally initiated test in
progress.
Running a test can af
fect your application data or may
cause your application session to be dropped depending
upon front-end processor, time-out parameters, etc. since
no data or acknowledgment messages will be transmitted
while the test is in progress.
Abort
The Abort
selection allows you to abort a test that is
running.
The DSU cannot run any other test until the test
in pr
ogr
ess 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 for the DBM
branch. This selection terminates all tests running
on the remote DSU or DBM.
After selecting either Selective or Subn, the test is
terminated and the DCP displays the message
Command
Complete.
Device Test
The Device (Devic) T
est uses a test pattern generator
built into the DSU. When testing the DBM, the DBM must
be in Idle mode, with no call in progr
ess befor
e running a
Device T
est.
NOTE
On power-up, the DSU sends
out polls to verify that a DBM is
installed. It then initiates a
Device Test on itself and the
DBM. The results of the tests
appear momentarily on the
DCP’s LCD.
Loopback
The Loopback (Lpbk) branch displays four loopbacks:
• Local Loopback (LL) – DSU only
• DTE Loopback (DTE)
• Digital Loopback (DL)
• Remote Digital Loopback (RL) – DBM only
Figure 4-3 shows where each loopback occurs on the
circuit. Refer to the figure as you read about loopbacks.