user manual

Zhone Technologies / 5-1
Diagnostics T1 loopbacks
Chapter 5
Diagnostics
This chapter describes how to perform loopbacks on the Z-Plex unit interfaces. It also
describes the system’s LEDs. It includes the following topics:
T1 loopbacks page 5-1
BER testing page 5-3
Data port loopbacks page 5-4
FXO and FXS ports loopback page 5-6
LED indicators page 5-9
5.1 T1 loopbacks
The T1 interfaces support local and line (network) loopbacks:
• During a line (network) loopback, the signal is looped back to the network. The receive
T1 signal is looped onto the transmit T1within the framer chip.
• During a local loopback, the signal is looped back to the user. The transmit T1 signal is
looped onto the receive T1within the LIU.
The Z-Plex unit supports ESF loopback detection sent from remote equipment. These codes
are ANSI T1.403 compatible with DS1 networks and allow the unit to detect a latching
loopback to remote DS1 equipment. The Z-Plex detects payload loopback (PLB), network
loopback (NLB), and line loopback (LLB). The Z-Plex also supports TR 54016 for loop up
and loop down cases.
Figure 5-1 on page 5-2 illustrates T1 loopbacks on the Z-Plex unit.