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DSU Operations
5-233610-A2-GB41-60 March 1999
In a point-to-point network only, Remote Digital
Loopback can also be initiated by the DTE by raising
Pin 21 of the EIA-232-D/V.24 interface or Pin N of the
V.35 interface, provided the Remote Digital Loopback by
DTE (RL by DTE) configuration option is enabled. When
testing a DBM, the DBM must be in Dial Backup mode to
realize this capability.
The Remote Digital Loopback command is not available
when the LPDA-2 configuration option is enabled.
NOTE
If the Bilat Lpbk (Bilateral
Loopback) configuration option is
enabled, requesting a Remote
Digital Loopback on a port
automatically initiates a DTE
Loopback on the port as well.
Requesting an aggregate Remote
Digital Loopback automatically
initiates a DTE Loopback on
all
of
the ports.
To access Remote Digital Loopback from the top-level
menu, make the following selections:
• Local (F1)
• Test
• DBM (select active core)
• Lpbk
• RL
• Port Select (when not operating in single-port
mode)
• Trib Address (multipoint control DBM only)
For TDM or MCMP mode, the following additional
menu appears:
F1
Port Number:
Prt1 Prt2 Prt3
F2
F3
Prt5 Prt6 AggrPrt4
In TDM or MCMP mode, raising Pin 21 on Port 1
initiates an aggregate loopback. This loopback is
performed on the DDS circuit unless a dial backup session
is active.
When in MCMP mode, the port selected is not
necessarily the port placed in loopback at the remote
location. For example, if a channel assigned to Port 2 locally
is assigned to Port 3 remotely, then selecting Port 2 places
Port 3 at the remote location in loopback.
When a DSU (control or tributary) originates Remote
Digital Loopback, both the originating DSU and the
targeted DSU enter Test mode. On a multipoint circuit, all
other tributaries are also placed in Test mode. No other
test can be run at the originating DSU or the targeted DSU
until the Remote Digital Loopback is aborted.
Results
The DBM does not generate the test results.