Verilink PRISM 4101 (34-00230) Product Manual - Manual (Page 33)

Main Menu 21
Loop Mode
Allows you to choose how the data will be looped back. The choices are
Bidirectional or Unidirectional.
When set to Unidirectional, the NET receive data is looped back to the NET as
NET transmit data and continues to pass through the data port to the DTE as
shown in Figure 3-15. Transmit data from the DTE is terminated.
Figure 3-15 Unidirectional Loop
When set to Bidirectional, the NET receive data is looped back to the NET as NET
transmit data as shown in Figure 3-16. Transmit data from the DTE is looped back
through the data port as receive data to the DTE.
Figure 3-16 Bidirectional Loop
During dial backup, the loop mode field is ignored and all loops are unidirectional.
this allows testing of the DDS interface during dial backup without disrupting the
DTE/DBU data path.
Local Loop
The choices are On and Off. This loop occurs at the DDS network interface as a
bidirectional loop. It returns the DDS receive data to the DDS transmit line and the
PRISM 4101 transmit data to the unit receive data output.
In TxPORT mode, local loop functions differently. It is always a unidirectional loop,
implemented at the DTE interface. This allows the end-to-end data link to remain
operational during the loop.
V.54 Loop
The choices are On and Off. This loop occurs at the DTE data port interface and is
activated upon receipt of inband V.54 loop codes for at least two seconds followed
by all ones in the network receive data stream. This loop is unidirectional and
retransmits the PRISM 4101 received data on the unit transmit data including the
remapped loop code. Receive data is unaffected (but includes the modified loop
codes) and circuits DSR and DCD are Off. You may instruct the unit to transmit
inband V.54 loop code to the remote end unit causing it to enter a V.54 loop.
DTE NET
Line Loop
DTE NET Local Loop
✍
DTE NET
Local Loop
✍
DTE NET
Local Loop
(TxPORT Mode)
Data & Rcv FDL
Data & Xmt FDL