Remote Digital Loopback; Bilateral Loopback - Paradyne COMSPHERE
3610 User Manual

Remote Digital Loopback

Remote Digital Loopback (RL) supports testing by an
external device, such as a protocol analyzer connected to
the local DSU's DTE interface. Data input is sent to the
remote DSU and returned for error detection.
In Remote Digital Loopback, the local DSU (control or
tributary) puts the remote DSU into Digital Loopback. A
control DSU can originate Remote Digital Loopback on a
point-to-point or multipoint network. A tributary DSU can
originate Remote Digital Loopback in a point-to-point
network only. RL does not appear when in Remote mode.
Remote Digital Loopback can also be initiated by
receiving a V.54 pattern that starts a Digital Loopback.
For point-to-point configurations, enable configuration
options V.54 Lpbk (V.54 Loopback – Table 4-1) and
RespondRDL (Respond to Remote Digital Loopback –
Table 4-4).
The control DSU can send a Digital Loopback to a
multipoint tributary and perform a Remote Digital
Loopback on the multipoint tributary. A Digital Loopback
cannot be initiated from a multipoint tributary.
DTE
DTE
COMSPHE RE
DL on a
Port
DTE
COMSPHE RE
3610-A2-GB46-60
LL
3610
Control
DSU
Figure 3-3. Loopbacks, Example 1
DL on
Aggregate
3610
Control
DSU
Figure 3-4. Loopbacks, Example 2
December 1996
When a DSU (control or tributary) originates Remote
Digital Loopback, both the originating DSU and the
targeted DSU enter Test mode. No other test can be run at
the originating DSU or the targeted DSU until the Remote
Digital Loopback is aborted.

Bilateral Loopback

Bilateral Loopback combines Digital (DL) and DTE
loopbacks and operates simultaneously in the same DSU.
For point-to-point configurations, use the Bilateral
Loopback (Bilat Lpbk) configuration option from the
General (Gen) configuration option set (Table 4-4).
Once the loopback test begins, the message Command
Complete appears. If the Bilateral Loopback
configuration option is activated, requesting a Remote
Digital Loopback (RL) or Digital Test (DT) automatically
initiates a DTE Loopback. A Digital Test (DT) starts a
Remote Loopback which causes a Bilateral Loopback at a
remote site.
RL on
Aggregate
NETWORK
COMSPHE RE
3610
NETWORK
COMSPHE RE 3610
Tributary
DSU
Front Panel Operation
RL on a
Port
DTE
Tributary
DSU
496-14493-02
DTE
RL
DTE
Bilateral
Loopback
496-14762-01
3-11