Extreme Networks WM-4T1i manual Data Data out Framer, Framer Data out

Monitoring T1 Physical Link

Near-end Loopback Modes

The near-end of the link can be enabled for the following three loopback modes:

•Local

•Network Line

•Network Payload

The local loopback mode reflects the data stream internally to the near-end. The network line loopback mode reflects the signal to the far-end. The network payload mode reflects the data carried in the signal and regenerates framing information back to the far-end.

Local T1 Port

Data in

Data out

Framer

Figure 2-2:Local loopback mode

Remote T1 Port

Framer

Data out

Data in

XM_011

Local Loopback Mode. When the local port is enabled for local loopback, the local data stream goes into the framer and the framing bits are inserted into the data, but the data is not transmitted to the remote end. Instead, it is sent back through the local framer, the framing bits are discarded, and the original data is returned. This mode tests the local end.

WM-4T1i Module Installation and User Guide 2-7