User manual

Diagnostics & Troubleshooting
Testing Low-Speed Interface Operation
7-28 July 2004 Wide Bank 28 DS3 - Release 2.4
Testing the Network to the Far-End Through a Low-Speed Drop
This test uses a Wide Bank at one end of the network to provide an NIU loopup of a low-speed
drop at the far end. In the example below, a Wide Bank is used at both ends of the DS3 network,
providing a simple illustration of how the far-end loopup works.
NOTE: This test works with range and all parameters of the ds1 (ls) command but
usually is just as effective using only the n parameter (testing only one ls circuit), which
leaves all the other low-speed circuits operational. This test’s best purpose is to test the
DS3 network, beginning at a near-end low-speed drop and ending at a far-end low-speed
drop.
Once an equipment loopback is established to the far-end with the ds1 [n|range|all] send loopup
or ds1 [n|range|all] send cbit loopup command, a ds1 [n|range|all] send prbs network command
will send a prbs pattern over the selected low-speed tributaries within the DS3 network. This
pattern will be looped back from the far-end. Note that the unselected low-speed circuits will
maintain normal traffic during this test.
To stop the test, issue a ds1 [n|range|all] send off command, then issue the appropriate
loopdown command to disconnect the equipment loopback at the far end.
To read the results of the test, issue an hour ds1 n command.
Figure 7-17 Testing the Network with a Send PRBS Network Command
Trans-
ceiver
Selector
M13
Framer
Trans-
ceiver
Relays
LS Card HS Card
Send AIS
Trans-
ceiver
Selector
M13
Framer
Trans-
ceiver
Relays
LS Card HS Card
Toward DS1/E1
DS3
DS3
Send PRBS
Toward DS3
Loop Detect
Must be Enabled
Relays
DS1/E1
DS1/E1
Local LS
Far-End LS
Relays
Near-End (Local) DS3
Far-End DS3
Send AIS
Toward DS1/E1