uucico problem with flow control

The Imaginative Moron paul at dialogic.UUCP
Wed Aug 16 06:15:06 AEST 1989

In article <208 at bulus3.BMA.COM> haugen at bulus3.BMA.COM (John M. Haugen) writes:
>I recently have been having problems with uucico having problems receiving
>large files from my news feed.  When run with Uutry, I see bunches of
>"alarm " messages and eventually the transfer fails. 
>My suspicion is flow control is not being used/set up correctly by uucico.
>This in turn is causing a loss of data.
> [ stuff about using XON/XOFF for flow control ]
>John M. Haugen             Domain:  haugen at BMA.COM
>Bull Micral of America     UUCP:    ...!uunet!bulus3!haugen
>1970 Oakcrest Ave. #300    ATT:  612-633-5660
>St. Paul, MN  55113-2624

OK, let's clear up a few misconceptions first, then get down to the
nitty gritty.... 

uucp does not use xon/xoff. It has a number of internal packetizing
protocols (most common being g-protocol) that use ACK/NACK and
timeouts to re-send corrupted packets. Think about it - how can it use
XON/XOFF ? Those charaters could be a legitimate part of the data

The problem you are having is because the standard ISC asy driver
using regular PC serial ports cannot deal with prolonged bursts of
9600 (or even 4800) packets. It loses characters, thus causing both
receiver and sender to pause; the sender waiting for an ACK, teh
receiver waiting for more data (it has a packet size and counts).
Eventually, the receiver times out, sends a NACK, and the sender
re-tries.  This holds true even when the Telebit is spoofing g-protocol.

The fix is to change the asy driver and the serial card UART. We have
a driver which we got via a reference from this group. You can get it

Macro Computer Solutions

Ask for the SDK serial driver for 386/ix.

It's $50 for the driver - well worth it.  With 16550 SIO chips in a
standard PC serial card, it will do 19.2K easily.  16550 have a FIFO
in them which the driver detects and enables. They are plug compatible
with the more usual 16450 (I think that's the number ..).  Try and get
a card with one on. I've heard that National are discontinuing this
chip, but have not had this confirmed. 

If 9600 is acceptable, you may be able to do it with a regular serial
card and the new driver. Also, the above driver supports dumb multi-line cards such as the Digiboard COM8.

Hope this helps.
Paul Bennett			paul at dialogic.UUCP, ..!uunet!dialogic!paul
Dialogic Corp, 129 Littleton Road, Parsippany, NJ 07054 (201) 334-8450 x 194
"Englands Monarchy is how old ? 1000 years ? Jesus, you guys must have
a hell of a lot of laws! " 			Anon. sysadmin

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