Nortel Networks Circuit Card Manuale Utente

 NT5D33 and NT5D34 Lineside E1 Interface cards

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.

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 

 demonstrates how an external 

loopback is applied to the E1 link.

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

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