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27 — Loopbacks
2902 MainStreet Technical Practices
27-11
May 2002 90-2906-01
27.4
Data circuit loopbacks
The RS-232 DCM, Codirectional DCM, and subrate and super-rate circuits of the
X.21 and V.35 DCMs support loopbacks B and C.
Loopback B for RS-232, X.21 and V.35 DCM circuits
Loopback B for the RS-232, X.21 or V.35 DCM is a bidirectional loopback that
extends from the DX and loops back in the gate array itself, as close as possible to
the network side (see Figure 27-11). Each circuit on the RS-232 DCM can be looped
back individually.
Figure 27-11 Loopback B for RS-232, X.21 and V.35 DCMs
Loopback B Codirectional DCM circuits
Loopback B for the Codirectional DCM occurs at the tributary output (see
Figure 27-12). While Loopback B is applied to a Codirectional DCM circuit, 8 kHz
timing is turned on and all ones is turned off. Even if the Codirectional DCM circuit
has been configured not to generate 8 kHz timing, it generates 8 kHz timing during
the test. Even if the Codirectional DCM circuit has been configured to generate all
ones, it does not generate all ones during the test.
Caution —
Initiating a data circuit loopback may cause the data
session on the selected circuit to be dropped.
Data
device
2902 MainStreet
DCM
Control
card
DX
Gate
array
Loopback B
8855
Gate
array
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 ...