Paradyne COMSPHERE
3610, Руководство оператора

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DSU Operations
4-19 3610-A2-GB91-90 July 1999
Digital Loopback
Digital Loopback (DL) is used for manual testing of
the remote end of the circuit. For example, a Digital
Loopback may be required in order to complete an
external bit error rate test (BERT) from the remote DSU.
The local DSU receives test data, loops it back to the
transmitter before the DTE interface, and returns it to the
network (Figure 4-6).
For the DSU, Digital Loopback is session-disruptive
except when a dial backup session is active. It is used to
condition the DSU for testing to determine whether the
DSU connection to the network is functioning properly.
The Digital Loopback command requires a DDS network
circuit between two DSUs. DTE connections to the DSUs
are not required.
Digital Loopback (DL) can be initiated by:
•
Selecting DL from the Lpbk submenu in the Test
branch menu.
•
Receiving a V.54 loopback pattern by enabling
configuration options V.54 Lpbk (V.54 Loopback)
and RespondRDL (Respond to Remote Digital
Loopback).
Selecting Aggr (Aggregate) loops back the
user-transmitted data as well as the in-band secondary
channel transport data (if nondisruptive diagnostics are in
effect), thereby disrupting in-band secondary channel
transport communications. Selecting Prt1 (Port 1) causes
the loopback to occur further into the data router at a point
where the in-band secondary channel transport has already
been extracted from the user-transmitted data, and only
the user-transmitted data is looped back. In-band
secondary channel communications are preserved.
To access Digital Loopback from the top-level menu,
make the following selections:
•
Local (F1), Remot (F2) and Address
•
Test
•
DSU (select active core)
•
Lpbk
•
DL
•
Port Select (when not operating in single-port
mode)
NOTE
When the local DSU initiates
Digital Loopback to a remote DSU
(via Remote mode), the remote
DSU is placed in Test mode. The
local DSU, though, is not in Test
mode, and another test, such as a
BERT, can be initiated at the local
DSU.
Results
The test result is a message indicating whether or not
the loopback executed successfully.
Figure 4-6. Digital Loopback