ADTRAN T200 IDSL Manual de usuario descargar pdf (Pagina 4)

4 Issue 1, May 2004 61292023L5-5A

DDS Loopback

The Total Reach OCU-R works in conjunction with the

Total Reach DDS CO unit in response to network

initiated latching and non-latching loopback sequences.

Latching Loopbacks

The OCU-R will respond to OCU and NIE latching

loopback sequences at all rates including 64 kbps.

Non-Latching Loopbacks

The OCU-R will only respond to OCU non-latching

loopbacks at 56 kbps and all sub-rates.

• Upon receipt of an OCU or NIE loopback, the

OCU-R will initiate a loopback towards the

network.

• Upon receipt of a CSU loopback, the OCU-R will

reverse Tip and Ring sealing current polarity

towards the 4-wire DDS interface.

Legacy latching and non-latching loopbacks are defined

in TR 62310 and ANSI T1.107.

False Loopback Immunity

ADTRAN’s protected loopback family of channel units

include an algorithm compatible with SARTS,

Hekimian, TPI, and other test systems that virtually

eliminates false latching loopback occurrences. This

algorithm is always enabled at 64 kbps. In addition,

ADTRAN’s protected loopback family features a

protected loopback mode for further false latching

loopback protection.

Protected Loopback

Protected loopback prevents false latching loopbacks

when the latching loopback sequence is embedded in

customer payload data. At 64 kbps, the Total Reach

OCU-R will respond to the legacy latching loopback

sequence defined in TR 62310 and ANSI T1.107, or the

protected loopback sequence defined in T1E1.2/99-

007R1.

When the Total Reach DDS CO unit is provisioned for

protected loopback, the idle code preamble must be sent

prior to an OCU, CSU, or NIE latching loopback

sequence, otherwise the Total Reach OCU-R will not

respond.

Test equipment should support T1E1.2/99-007R1 to

perform testing at 64 kbps when protected loopback is

enabled. Table 2 details the latching loopback sequence

requirement when protected loopback is enabled.

Minimum of 35 TIP bytes required to disable established

latching loopback.

x = Don't care bit

Wiring

The Total Reach OCU-R can be housed in any standard

T200/T400 shelf or standalone housing, such as

ADTRAN T200/T400 Single Mount Housing, part

number 1212007L1.

Connections are made using screw-down connectors on

the terminal strip located at the rear of the housing.

Figure 5 illustrates the circuit card pinout and Tab le 3

shows the wiring designations for the Total Reach

OCU-R.

The unit should be wired as follows:

• Network pair to terminal strip TR and TT positions

• To Customer and From Customer pairs through

customer 8-pin modular connector

To Customer (DRT, DRR) and From Customer

(DTR, DTT) to designated terminal strip positions

No rate selection is necessary for the Total Reach OCU-

R.The unit automatically adapts to the service rate of the

Total Reach DDS CO unit.

Table 2. Protected Loopback Mode

Requirement T1E1.2/99-007R1

(Latching Loopback)

Sequence

Function

Byte Code Number of

Received

Bytes

Exit data

protocol

Idle - 11111110 Minimum of 35

Idle bytes

Clear existing

loopbacks

Transition in

progress (TIP)

X0111010

Minimum of 35

TIP bytes

Identify device

to be looped

Loopback select

code (LSC)

X1010101 - OCU

X0110001 - CSU

X1000001 - NIE

Minimum of 35

LSC bytes

Prepare to loop;

send MAP code

after 30 bytes

Loopback

enabled (LBE)

X1010110

Minimum of

100 LBE bytes

Activate

loopback

Far-End voice

(FEV)

X1011010

Minimum of 32

FEV bytes

1 2 3 4 5 6 7 8 9 ... 21 22

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ADTRAN T200 IDSL Manual de usuario Pagina 4

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