Avaya S8700 Maintenance Manual page 1402

Maintenance-Object Repair Procedures
To isolate a problem, set the loop back first at the loop-back point LB 1, and then
at the loop-back point LB 2, see
backs at as many points as your CSU capabilities will allow. Hard-wired loop
backs at the far end are not desirable, because the equalization-level adjustments
may cause problems.
Every part of this test is executed under firmware control and the result is sent
back to the maintenance software. The test is executed by sending digital data
through every DS1 channel on this DS1 facility.
This test is executed via the test ds1-facility UUCSSf external-loopback
command. It is not part of the long test sequence because it requires
modifications to the physical connectivity of the DS1 facility.
If there is only one DS1 facility available, system will not allow the last facility to be
busied out. In that case, the DS1 CONV circuit pack must be busied out before
executing this test.
For a standard-, duplex-, or high-reliability system (no PNC duplication), if there is
only one DS1 facility available, then this test can only be executed at the endpoint
that is closer to the media server relative to the neighbor DS1 CONV circuit pack
because of its impacts on the system control links. For a critical-reliability system
(PNC duplication) or for a system with multiple DS1 facilities, the test can be
executed at any DS1 CONV circuit pack.
If the test passes on a TN1654 DS1 facility, the round trip delay time will be
displayed in milliseconds in the Error Code field. The round trip delay time is
defined as the length of time in milliseconds it takes for the firmware to receive the
test pattern after it has been sent. This measurement is taken on the last DS1
channel tested.
DS1CONV
A
Test starts here
Figure 8-28. Loopback Points for Test #799
8-680 Issue 1 May 2002
Figure 8-28
LB 1 LB 2
CSU A
DS1 Facility
and Figure 8-25. Place the loop
CSU B
DS1CONV
B
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