Bay Networks 3395A, Configuration Manual

Page: 135 / 146

Modem Control Signal Interaction
893-826-A A-5
Figure A-3. State diagram for dial-out modems
The following list describes the sequence of signals for this application:
• Server asserts DTR when the remote connection is formed.
• Server permits data flow after the assertion of DTR.
• User may now dial out.
• Server deasserts DTR if DCD is not asserted within 120 seconds of the
formation of the server connection. The server increments a failed call
count. If the failed call count reaches the value set for the server
PASSWORD LIMIT characteristic, the server logs out the port and
deasserts DTR.
• Server performs the disconnect sequence if DCD is deasserted for more
than the period of time specified by the DCD TIMEOUT characteristic
(default is 2 seconds).
• Server performs the disconnect sequence if the session is disrupted.
Dial-in/Dial-out Modems that Support RNG
This is the standard configuration for dial-in/dial-out lines that support the
RNG modem control signal. The server asserts the DTR signal in response to
the assertion of the RNG modem control signal or the formation of a remote
connection.
Figure A-4 shows the modem states that the port enters as it
observes or asserts various modem signals (in the diagram, circled items
indicate port states and arrows indicate activity).
DCD not observed
for 120 seconds,
increment failed
call count
Failed call count
equals password
limit
Make
conection
DCD not
observed
for timeout
period
Observe
DCD high
Deassert
DTR
Run
Start
Assert
DTR,
allow data
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