Loopback Definition; Loopback Definition; Line Loopback; Line Loopback - ADTRAN Total Access 5000 Deployment Manual

Total Access 5000 Business Services Deployment Guide

Loopback Definition

A loopback and Bit Error Rate Test (BERT) provide the ability to insert a known traffic pattern
and verify the error‐free performance of the circuit at given points in the system.

Line Loopback

A line loopback (see Figure G‐1) loops all of the received data back toward the network (DS3
payload and DS3 data). The transmitted data is the identical data that is received and is not
reframed or regenerated. This tests right up to the DS3 interface of the module.
The line loopback can be local to the access module.

Payload Loopback

A payload loopback (see Figure G‐2) performs the same functionality as the line loopback,
except the payload loopback sends the received data through the framer, where it is reframed
and regenerated, prior to being transmitted back out towards the network. This test also
verifies the internal hardware of the module.
The payload loopback is locally initiated.
NOTE
The DS3 does not support a payload loopback.
G-2
DS-3 Facility

Figure G-1. Line Loopback Diagram

Line Loopback
DS3 Interface
Framer
65K510DEP08-1A