Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!amdcad!rpw3
From: rpw3@amdcad.AMD.COM (Rob Warnock)
Newsgroups: comp.dcom.modems
Subject: Re: TrailBlazer and UUCP
Summary: FTP (KA9Q + 4.3bsd/SLIP) >= UUCP speed.
Message-ID: <22523@amdcad.AMD.COM>
Date: 2 Aug 88 11:45:01 GMT
References: <12793@mimsy.UUCP>
Reply-To: rpw3@amdcad.UUCP (Rob Warnock)
Organization: [Consultant] San Mateo, CA
Lines: 42

+---------------
| From: chris@mimsy.UUCP (Chris Torek)
| The g-protocol spoofing is neat, but here is a thought:  Would it be
| worthwhile to write an `h' protocol, specifically designed for
| half-duplex high-speed not-necessarily-error-free modems?
+---------------

Just for comparison, note that by diddling "max seg size" and "window"
parameters on Phil Karn's (KA9Q) TCP/IP package, I was able to get FTP
throughputs (disk to disk) of 875 bytes/sec (user data) between a PC/AT
running KA9Q and a VAX 11/780 running SLIP (4.3 + recent Karels/Jacobson
upgrades), with 9600 baud serial lines on both TB+'s. (Haven't tried 19200.)

Note that when you count the 40 bytes of TCP/IP and the 1 byte of SLIP,
it was getting 875*(512+40+1)/512 ==> 945 bytes/sec through the modems,
which is over 98% of what a 9600 baud async line will do. Saying it
another way, the data flow never stopped. (And you could see that on the
breakout box I was watching. All the other parameter settings "stuttered"
quite a lot more.)

The params which got that 875 B/s throughput (VAX to PC) were MSS = 512,
window = 4096 (i.e. 8 packets).

Note that this equals or betters 9600 baud UUCP throughputs on the TB+,
even with UUCP protocol turned on. (TB's don't have any SLIP support yet,
and anyway it wouldn't have helped, as it was the RS-232 link which was
saturated. You need SLIP header compression in the host, you really do.)

The only trouble is, nobody (certainly not me!) has wrapped KA9Q/4.3BSD/
SLIP/FTP with the control software to let it autodial from one host to
another and play exactly the sort of role uucico plays now. That would be
a beginning to superseding UUCP. (Imagine, dialup SMTP, no "!" addresses...)

But since you can have a Telnet session open at the same time, it *does*
let me read news while I'm waiting for big files to move...

Rob Warnock
Systems Architecture Consultant

UUCP:	  {amdcad,fortune,sun}!redwood!rpw3
ATTmail:  !rpw3
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