bill@twg.bc.ca (Bill Irwin) (06/30/91)
I have just installed by first V.32/V.42bis into a uucp system (a
GVC Super Modem). I am still trying to determine a set of
default settings for the modem that will allow a reliable
connection to my news feed (running V.32 MNP5) and easy
interactive dialout to a multitude of different modems at client
sites. So far the best I've been able to do creates a situation
where certain remote modems seem to interpret the handshaking as
a BREAK signal and the port cycles off the link baud rate before
the login: appears. This is a minor inconvenience to have to
send a manual BREAK to get the port to cycle back to the right
baud rate.
I run "uutraf" daily which summarizes the uucp traffic and have
noticed since installing the GVC that the Cps rate for transfers
to my news feed have gone up to 1,200 Cps, while the rate for
receiving files has only gone to 400 Cps maximum. The port that
the GVC is on is configured to run at 19200 with ixon ixoff
-ixany during a login session. This agrees with the Xon/Xoff
flow control selected on the GVC (\Q1). However, during a
dialout connection I checked the status of the port (one on a
DigiBoard with modem control) and noticed that it was running
-ixon -ixoff -ixany. Without flow control there are going to be
many bad packets which will cause many retries and slow the
throughput considerably. One question I have is how do you turn
on flow control during an outgoing uucp session? Since the port
is modem controlled, you can't send an stty command to the port
unless a carrier is present. Perhaps using RTS/CTS flow control
is the solution?
The only way I could figure to get uucp to dial out at 19200 was
to put that speed as the baud rate for the site in the Systems
file entry, even though the modem will produce a CONNECT 9600
MNP5 COMPRESSED message. Fortunately my feed has their login
prompt configured to display the baud rate of the port, so the
uucp dialer does actually see "19200" and continues the login
chat. Is this the way to get a dialout modem's serial port speed
at 19200 so that a compressed link at 9600 has a chance of better
throughput?
The settings that I have altered on the GVC are as follows:
new setting [default setting]
B2[B0] DCE speed will be changed according to the speed of the
remote modem. [DCE speed will be fixed according to
DTE speed.]
&S1[&S0] DSR operates according to RS-232C spec. [DSR remains
on all the time.]
%T1 Trellis code enabled. (default)
\A3 256 character maximum MNP block size. (default)
%C1[%C0] Enable Class 5 operation. [Disable class 5.]
\C1[\C0] Buffer all data for 4 seconds, until receiving 200
characters or a packet is detected. [Do not buffer
data.]
\N6[\N0] Auto-reliable V.42/MNP/Normal link. [Normal link only.]
\V1[\V0] Extended responses. [No extended responses.]
There are many other settings that I have left at the factory
default in an effort to keep the possible combinations down to a
number that can be dealt with by humans. Any suggestions would
be appreciated.
--
Bill Irwin - The Westrheim Group - Vancouver, BC, Canada
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