Paradyne COMSPHERE 3611 - Manual (Page 23)

COMSPHERE 3600 Series Data Service Units
3-8 September 1996 3610-A2-GB48-50
Loopbacks
Loopback (Lpbk) provides four loopback tests.
Figure 3-3 shows the direction of each loopback on the
circuit. Refer to Document No. 3610-A2-GB46 for
additional loopback information.
Local Loopback
Local Loopback (LL) is session-disruptive; performing
the test disrupts data. The DTE may run a test to
determine if the DTE to DSU connection and the DSU
itself are functioning properly.
•
The DSU must be connected to the DTE.
•
Network connection to the DSU is not required.
•
For TDM, MCMP, or Bridge mode, the entire data
stream is looped back and all six ports are in Local
Loopback.
DTE Loopback
DTE Loopback (DTE) loops back the data path at the
DTE/DCE interface on a per-port basis without affecting
the operation of the remaining ports. The DSU with TDM
or MCMP permits one active test at a time.
Digital Loopback
Digital Loopback (DL) allows manual testing with the
remote end of the circuit. DL can be initiated from a
control or a point-to-point tributary.
Selecting one port or all active ports (Aggr) loops back
the user-transmitted data and the in-band secondary
channel transport data when nondisruptive diagnostics are
in effect. This disrupts in-band data transport
communications.
In Bridge mode, a Basic mode loopback occurs without
port selection. For MCMP mode, using the NetIntf
selection to perform a Digital Loopback is not a valid
command.
Remote Digital Loopback
Remote Digital Loopback (RL) supports testing by an
external device, such as a test pattern generator connected
to the local DSU’s DTE interface. This tests the local
DSU and the DDS circuit.
•
In TDM or MCMP mode, asserting power to Pin 21
on Port 1 initiates a V.54 aggregate loopback. This
loopback is performed on the DDS circuit unless a
dial backup session is active.
•
In MCMP mode, the port selected is not
automatically the port placed in loopback at the
remote location. If a channel assigned to Port 2
locally is assigned to Port 3 remotely, Port 3 at the
remote location is placed in loopback.
To abort a Remote Digital Loopback, issue an Abort
command to the control DSU.
496-15049
Control
DSU
DTE
DL on a
Port LL
COMSPHERE 3610
DTE NETWORK
RL on
Aggregate
RL on a
Port
COMSPHERE 3610
Tributary
DSU
DL on
Aggregate
Figure 3-3. Loopbacks Example