User`s guide

Performing Loopback Modes and Pattern Tests
6-11
7800-A2-GB26-80
May 1999
External DTE Loopback
DTE External Loopback loops the user data port back to the DTE interface on a
per-interface basis without affecting operation of the remaining interfaces. This
loopback is located as close as possible to the customer interface (see figure
below).
DSU CSU
DTE
Interface
Aggregate
DTE
Port
DDS
Network
Port
496-14931
DTE
Port
DDS Frame Relay Access Unit
Using Pattern Tests (for All Devices)
Pattern tests enable a device to send or monitor a known bit pattern. These tests
generate industry-standard, MIB-defined bit patterns that can be used to
determine whether information is being correctly transmitted across a circuit.
These patterns can be sent by the Network T1 and Data Ports interfaces.
You can use a pattern test by itself to test one end of a circuit, or you can use a
pattern test with a loopback mode to test both ends of a circuit. The following
figure demonstrates a pattern tests that tests one end of a circuit.
DSU/CSU
Sending a QRSS
Test Pattern
DSU/CSU
Monitoring a QRSS
Test Pattern
DEVICE A
DEVICE B
T1
NETWORK
496-15096