Newsgroups: comp.mail.uucp
Path: utzoo!utgpu!watserv1!maytag!xenitec!iguana!merce
From: merce@iguana.uucp (Jim Mercer)
Subject: Re: Using UUCP over international phone lines
Message-ID: <1991Jan24.033322.7924@iguana.uucp>
Keywords: satellite packet-size acknowledgment delays
Organization: Ed (the iguana) Memorial Society
References: <267@fgh.fgh.oz.au>
Date: Thu, 24 Jan 91 03:33:22 GMT

In article <267@fgh.fgh.oz.au> michael@fgh.fgh.oz.au (Michael Coyne) writes:
>I am using UUCP between two 4800 baud MNP4 modems - one in Holland, and
>the other in Sydney, Australia.  My effective throughput is only about
>2400 baud.  I suspect that this is due mainly to UUCP using a small
>packet size, with relatively frequent pauses to wait for
>acknowledgments which have to travel halfway around the world.
>Examination of the TD/RD lights on my modem seems to confirm this -
>with a short burst on TD, followed by a longish pause, then a flicker
>of RD.  The remote machine is a mostly idle Tower 650, but even it
>should be able to respond to UUCP fairly quickly :-).
>
>Has anyone had a similar experience, and able to offer me any advice
>about how to improve my throughput?  At $1.60/minute, and with Megabytes
>to ship, every little bit helps.
>
>The sort of areas where I am hoping I might be able to do something are:
>
>1. Tell UUCP to increase its packet size.  With a reliable modem connection,
>acknowledgements could be sent much less frequently.  I know there are
>e, f and g protocols for UUCP, but I am not which is good for what - or
>even how to activate them.
>
>2. Use a completely different file transfer protocol.  Does GNU have a
>UUCP look-alike?

i experienced the same type of performance loss when trying to get g protocol
to work over X.25.

is the link "transparent" or does it have an underlying protocol like X.25?

here's a couple of things you can try:

1) make sure the "windows" variable is set higher than 3 (7 preferably)
   windows can be changed by examining the source (if you have it)
   or with a debugger (and some assistance from the tech people providing
   your unix binaries this is what i did for SCO Xenix 2.2.1)
   a low windows value means that the uucico's will wait for an acknowledge
   from packet n+1 after sending packet n+3.  bumping it to 7 means
   more data is in transit and it can live with a longer acknowledge time.

2) use another protocol.  if the link is kept clean by hardware (MNP?)
   you could use something like the x, f or e protocols that do less
   error checking and basically just stuff the file down the pipe with
   a checksum at the end of the file.

hope this helps.

-- 
[ Jim Mercer   work: jim@lsuc.on.ca  home: merce@iguana.uucp  +1 519 570-3467 ]
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