Nortel Host Tools New Features Manual page 4

Annex Communications Server R7.1B and Annex Host Tools R14.2 Release Notes
DSR Signal
The use of DCD and DSR signals has been split across two parameters:
need_dsr and control_lines. If the parameter need_dsr is set to Y, DSR
must be asserted to establish a connection on a port. If the parameter
control_lines includes modem_control, that is, the control_lines
parameter is set to both or modem_control, DCD must be asserted
to establish a connection. Separating control of these two signals
provides more flexibility in the use of modem signals.
New Value for output_flow_control
The NA per-port parameter output_flow_control allows the new
value both. This setting (if control_lines is set to flow_control or to
both) enables both in-band (XON/XOFF) and out-of-band (CTS/
RTS) flow control on the Annex III and Micro Annex CD180 serial
communications chip. These methods of flow control are independent
and have no overhead since they are handled by the CD180's
hardware rather than in software.
Setting output_flow_control to both enables both of these flow
control methods by default. It is then up to the user (via stty), or to
TELNET or rlogin protocol to disable the XON/XOFF portion of the
flow control if the remote modem is capable of out-of-band signaling,
and thus does not need the in-band flow control.
Since the standard character MIB doesn't support both forms of flow
control at the same time, you can't currently set this option via SNMP,
and a port with output_flow_control=both will lie to the host and
say it has hardware flow control enabled when queried via SNMP.
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