27 — Loopbacks
27-4
2902 MainStreet Technical Practices
90-2906-01 May
2002
For 2702 and 2703 MainStreet DTUs that support super-rate, super-rate circuit
loopbacks can only be applied while the circuit is connected. If a loopback is applied
to either port while neither is connected, the system displays the following error
message: “Connect super-rate circuit before applying loopbacks.” If a loopback is
applied to one port while the other is involved in a super-rate connection, the system
displays the following error message: “Loopback invalid: other port involved in
super-rate connection.”
Loopback A
Figure 27-2 shows loopback A, which occurs simultaneously on both circuits (DTU
ports A and B). Loopback A extends from the DX on the Control card and loops back
on the 2B1Q line driver located on the 2B1Q module.
Figure 27-2 Loopback A for 2700 MainStreet series DTUs
Loopback B
Figure 27-3 shows loopback B, which is a bidirectional loopback that can be initiated
on either circuit (port A or port B). The signal from the Control card is looped back
within the DTU, in the DRAGA chip, at the end nearest to the 2B1Q module.
The signal from the data device is also looped back in the DRAGA at the end nearest
the 2B1Q module.
2902 MainStreet
2B1Q
module
Control
card
DX
2B1Q
line driver
DTU
DRAGA
Loopback A
16580
2B1Q
line driver
Summary of Contents for MainStreet 2902
Page 1: ...2902 MainStreet Network Termination Unit Release 1 0 H T E C H N I C A L P R A C T I C E S ...
Page 40: ...3 Mounting the unit 3 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 50: ...4 Ground and power connections 4 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 68: ...6 Connecting to the network 6 4 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 90: ...7 Connecting to data devices 7 22 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 108: ...10 Node management 10 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 150: ...14 CPSS 14 6 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 218: ...20 Codirectional DCM 20 6 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 234: ...22 HCM rate adaption 22 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 246: ...23 Cross connecting circuits 23 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 254: ...24 Visual indicators 24 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 266: ...25 Alarms 25 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 278: ...26 System diagnostics 26 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 298: ...27 Loopbacks 27 20 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 332: ...Glossary GL 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 343: ......
Page 344: ... 2002 Alcatel All rights reserved 90 2906 01 95 1820 01 00 C ...