Maintenance
4-193160-A2-GB21-50 January 1997
Starting a DTE Loopback
The DTE Loopback command (DLB) loops the
received signal on the DTE Drop/Insert (DSX-1) port
back to the DTE without change.
496-14317-02
CSUDSU
NETWORK
INTERFACE
DTE
(DSX-1) DLB
PORT 1PORT 2
ALL 1s
To perform a DTE loopback,
1. From the top-level menu screen, select Test.
2. From the Test screen, select Lpbk.
F1
Test:
Rlpbk Lpbk Ptrns
F2 F3
3. From the Loopback screen, press the key until
the DLB selection appears on the screen.
4. Select DLB.
F1
Loopback:
LLB PLB DLB
F2 F3
Test Started appears on Line 2. If a DTE
loopback is already in progress, the Already
Active message appears. If an invalid combination
of loopbacks is in progress, the error message
Invld Test Combo appears (see Table 4-8 for
valid loopback test combinations).
Starting a Repeater Loopback
The Repeater Loopback command (RLB) loops the
signal being sent to the network back to the DTE
Drop/Insert (DSX-1) and data ports. The signal is looped
back as close to the network interface as possible (after it
has passed through the framing circuitry of the
DSU/CSU). Framing CRCs and BPVs are corrected.
496-14318-02
CSUDSU
NETWORK
INTERFACE
DTE
(DSX-1) RLB
PORT 1 PORT 2
ALL 1s
To perform a Repeater loopback,
1. From the top-level menu screen, select Test.
2. From the Test screen, select Lpbk.
F1
Test:
Rlpbk Lpbk Ptrns
F2 F3
3. From the Loopback screen, press the key until
the RLB selection appears on the screen.
4. Select RLB.
F1
Loopback:
PLB DLB RLB
F2 F3
Test Started appears on Line 2. If a Repeater
loopback is already in progress, the Already
Active message appears. If an invalid combination
of loopbacks is in progress, the error message
Invld Test Combo appears (see Table4-8 for valid
loopback test combinations).