How to speed up UUCP?

[Bob Toxen]

In article <11913 at tut.cis.ohio-state.edu>, lvc at tut.cis.ohio-state.edu
> (Lawrence V. Cipriani) writes:
> I would like to get uucp to run much faster, both over modems
> and DATAKIT (TM) VCS.  9600 baud just ain't enough!  [How?]
> 
> [An] article in UNIX/World magazine that discussed speeding
> up uucp over modems.  [They didn't tell how.]
> 
> Thanks,
> Larry Cipriani, AT&T Network Systems and Ohio State University
> Path: ...!cbosgd!osu-cis!tut.cis.ohio-state.edu!lvc (weird but right)

First the obvious.  Ensure that your system AND THE UTTER (sic) system
can pump characters this fast.  Many systems cannot pump bytes at more
than 4800 baud (480 chars/sec).

The G protocol, which is the UUCP default, sends out 64 character packets.
It sends out a few (eight, I believe) and then these have to be sent out
(sometimes over a satellite), the other system has to read it, compute
checksums, send out an ACK packet, and the first system has to read it
before another packet can be sent out.

At high baud rates (and expecially over ethernet and the like) this will
kill performance.  Hack your own protocol that sends out much larger
packets.  Remember, the G protocol was in the days of 300 baud modems.

Remember also, that the tty line is in raw mode.  On V7 and (I think)
BSD systems the reading program is woken up on each character.  This
is very expensive to performance (and CPU utilization).  The System
V (and III) tty driver was modified to allow buffering of characters
read, even in raw mode.  Hack this into your V7/BSD system.  If you
have a non-System V UUCP on your SV system that fails to take advantage
of this feature it should be enhanced.

The folks Down Under modified their UUCP to send and receive
simultaneously, effectively doubling the bandwidth.

Well, I didn't say it was easy.
-- 

Bob Toxen	{ucbvax!ihnp4,harvard,cloud9!es}!anvil!cavu!bob
Stratus Computer, Marlboro, MA
Pilot to Copilot: What's a mountain goat doing way up here in a cloud bank?