ADTRAN T200 H2TU-R, Руководство по установке и обслуживанию

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5 61222026L1-5, Issue 1 61222026L1-5A
NOTE
For the BRG jacks, the Tx and Rx indications
relate to the direction of the DS1 signal to/from
the H2TU-R, respectively.
H2TU-R Network Loopbacks
The H2TU-R responds to multiple loopback activation
processes. First, loopback activation may be
accomplished using the control port of the H2TU-C or
H2TU-R.
Second, the H2TU-R will respond to the industry
defacto HDSL loopback codes as designated in the
ANSI document T1E1.4/92. A synopsis of the
method described by ANSI is presented in
Appendix A of this practice.
Third, the H2TU-R responds to T1 Network Interface
Unit (NIU) loopback codes as described in Bellcore
TR-TSY-000312 if the H2TU-R is optioned for NIU
loopback enabled. The NIU loopback codes are as
follows:
In-band Codes
Loop Up .......... 11000
Loop Down ..... 11100
ESF Codes
Loop Up .......... 0001 0010 1111 1111
Loop Down ..... 0010 0100 1111 1111
This unit contains smartloop technology. That is, it
constantly monitors the DSX-1 for a framing pattern.
The unit will initiate the proper loopback regardless of
how the loopback control sequence is sent (framed or
unframed).
Receiving the in-band codes for more than five
seconds or the ESF codes four consecutive times will
cause the appropriate loopback action.
The H2TU-R will respond to the loop up codes by
activating the NIU loopback from either the disarmed
or armed state. The loop down codes will return the
H2TU-R to a disarmed state from the armed or loop
up state.
Refer to Appendix A for more details on loopbacks
and loopback arming sequences.
Customer Loopbacks
In addition to the loopbacks in the direction of the
network, the H2TU-R may also be looped back in the
direction of the customer using the terminal control
port of either the H2TU-C, the H2TU-R or the LOC
LBK button on the Faceplate of the H2TU-R. The
H2TU-C can be looped using the REM LBK button
on the Faceplate of the H2TU-R. The H2TU-C and
H2TU-R Customer Side Loopbacks are illustrated in
Figure 3 .
NOTE
Network and customer loopbacks are governed
by the loopback time out option.
Figure 3. HDSL2 Loopbacks
DSX-1
H2TU-C
LOCAL
LOOP
H2TU-C Network-Side Loopback
H2TU-R
H2TU-C
LOCAL
LOOP
H2TU-R Customer-Side Loopback
H2TU-R
H2TU-C
LOCAL
LOOP
HT2U-C Customer-Side Loopback
H2TU-R
X
X
DS1
DSX-1
H2TU-C
LOCAL
LOOP
H2TU-R Network-Side Loopback or
H2TU-R NIU Loopback
H2TU-R
X
DS1
DS1
DS1
X
AIS
AIS
AIS
X = Signal Inactive
D = Data Sent
H2TU-C
LOCAL
LOOP
H2TU-R Bilateral Loopback
DS1 DSX-1
H2TU-R
(Metallic)