Nortel Circuit Card, Installation Manual, Page: 308 / 908

Page 308 of 906 NT5D33 and NT5D34 Lineside E1 Interface cards
553-3001-211 Standard 3.00 August 2005
Table 108 shows which test to run for the associated equipment.
Test 1, local loopback, loops the E1 link signaling toward itself at the
backplane connector. Test data is generated and received on all timeslots. If
this test fails, it indicates that the LEI is defective. Figure 59 illustrates how
the signaling is looped back toward itself.
Figure 59
MMI Local loopback test
Test 2, external loopback, applies an external loopback to the E1 link. Test
data is generated and received by the LEI on all timeslots. If test 1 passes but
test 2 fails, it indicates that the E1 link is defective between the LEI and the
external loopback location. If test 1 was not run and test 2 fails, the E1 link or
the LEI could be defective. To isolate the failure to the E1 link, tests 1 and 2
must be run in tandem. Figure 60 on
page 309 demonstrates how an external
loopback is applied to the E1 link.
Table 108
MMI Tests
Test number Equipment Tested Test Description
1 LEI Local loopback
2 E1 link, LEI, and E1
network External loopback
3 CPE device and E1
network Network loopback
E-1 link
Line side
E-1
interface
card
Customer
premise
equipment
(CPE)
Common
Equipment
System
External
network
E-1 link
553-1160