Extreme Networks WM-4T1i - Manual (Page 22)

2-8 WM-4T1i Module Installation and User Guide
Configuring the T1 Physical Link
Figure 2-3: Network line loopback mode
Network Line Loopback Mode. When the local port is enabled for network line
loopback mode, the received signal is sent back to the remote end without reframing
the data. This mode primarily tests the integrity of the line from the remote side.
Figure 2-4: Network payload loopback mode
Network Payload Loopback Mode. When the local port is enabled for network
payload mode, the framer removes the framing bits from the received signal and
recovers the transmitted data. This same data is then reframed and transmitted back to
the remote end. This mode tests the line and the local circuitry from the remote side.
Far-End Loopback Modes
The far-end of the link can be enabled for the following two loopback modes:
• Remote Line
• Remote Payload
XM_012
Remote T1 Port Local T1 Port
Framer
Data in
Data out
Data out
Data in
Framer
XM_013
Remote T1 Port Local T1 Port
Framer
Data in
Data out
Data out
Data in
Framer