152-388-100-02, Issue 2

Testing

 

 

LOOPBACK OPERATION

HiGain has a family of loopback options for analyzing circuit functionality. The loopback signal is transmitted and returned to the sending device for comparison. This allows you to verify the integrity of the HDSL2 channels to the H2TU-C, the H2TU-C DSX-1 interface, and the DS1 channels to the customer. Loopback options include:

•Generic Loopback (GNLB) options, including the SmartJack (SMJK) option (see Table 15 on page 40)

•Special Loopback (SPLB) options (see “Special Loopback Commands” on page 41) and the following command tables:

–Addressable Repeater Loopback commands: A1LB, A2LB, A5LB (see Table 16 on page 45)

–Addressable Repeater Loopback commands: A3LB, A4LB (see Table 17 on page 47)

Loopback commands can be initiated by:

•Selecting the loopback type using the MODE and SEL buttons on the H2TU-C front panel (or the Manual Loopback button on the H2TU-R)

•Selecting the loopback type from the Monitor Menu when connected to the craft port of the H2TU-C or H2TU-R

•Entering the loopback code (exceptions are COLB, DxLB, and RULB) into the test equipment connected to the H2TU-C or H2TU-R

HiGain supports multiple loopbacks, but a single loopback is the preferred method.

Generic Loopback Commands

The HiGain Generic Loopback (GNLB) commands allow you to use inband codes to loop up either NLOC (4-in-7) or NREM (3-in-7) towards the network. In addition, these inband codes loop up CREM (6-in-7) or CLOC

(5-in-7) towards the customer. Either loopup condition can be terminated (looped down) with the 3-in-5, SMJK loopdown code. All inband codes must be present for at least 5 seconds before the HiGain system responds. TLOS is a logic loopback caused by loss of the DS1 input from the CI.

Figure 26 summarizes the available loopbacks in the system, and Table 15 on page 40 summarizes the HiGain generic loopback commands. See “GNLB Test Procedures” on page 43 for the test procedures that apply when using the GNLB mode.

Activate loopback using

 

 

 

 

 

 

 

 

 

 

 

 

 

Activate loopback using

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

one of the following:

 

 

 

 

 

 

 

 

 

 

 

 

 

one of the following:

• MODE/SEL pushbuttons

 

 

 

 

 

 

 

NREM

 

 

 

 

 

• LBK pushbutton

• Maintenance Terminal

 

 

 

 

 

 

 

 

 

 

 

 

• Maintenance Terminal

 

NLOC

 

 

CREM

SMJK

 

 

CLOC

• Test Set

 

 

 

 

 

• Test Set

 

 

 

 

 

 

 

TLOS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

H2TU-C

 

H2TU-R

 

 

 

 

 

 

 

Network

Customer

Premises

 

Figure 26. Loopback Summary

H2TU-C-388 List 1

June 6, 2000

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