T7256 Agere Systems, T7256 Datasheet - Page 18

• Manufacturer Part Number: T7256
• Description: (T7234 - T7256) Compliance
• Manufacturer: Agere Systems

T7234 Single-Chip NT1 (SCNT1) Euro-LITE Transceiver
Loopbacks
The figure below shows the Layer-1 loopbacks that
are defined in ITU-T I.430, Appendix I and ANSI Speci-
fication T1.605, Appendix G. A complete discussion
of these loopbacks is presented in ITU-T I.430, Appen-
dix I.
14
Figure 9. Location of the Loopback Configurations (Reference ITU-T I.430 Appendix I)
A
TE1 = ISDN terminal
TE2 = Non-ISDN terminal
TA = Terminal adapter
NT2 = Network termination 2
NT1 = Network termination 1
LT = Line termination
TE1
TE2
4
R
A
S
TA
4
R = R reference point
S = S reference point
T = T reference point
U = U reference point
S
B1
NT2
3
B2
If a U-interface transparent B1 or B2 loopback is
requested via an eoc message, the proper channel is
looped upstream of the data flow matrix. All other
device functions are unaffected.
If a U-interface transparent 2B+D loopback is
requested via an eoc message, the 2B+D data will be
looped as close to the S/T-interface as possible. The
device forces all 0s in the echo channel towards the
TE.
T
Loopback
B1 or B2
2
C
A
2
3
4
NT1
C
Channel(s) Looped
2B+D channels
2B+D channels
U
2B+D, B1, B2
2B+D, B1, B2
B1, B2
B1, B2
Lucent Technologies Inc.
February 1998
LT
5-2482.a (C)