Path: utzoo!utgpu!watserv1!maytag!xenitec!zswamp!root
From: root@zswamp.fidonet.org (Geoffrey Welsh)
Newsgroups: comp.dcom.modems
Subject: Can we back up a sec?
Message-ID: <1288.27204357@zswamp.fidonet.org>
Date: Sat, 20 Oct 90 03:56:33 EDT
Organization: Izot's Swamp BBS - Kitchener, Ontario

   I noted with interest Larry Snyder's question about UUCP throughput over 
V.32 as compared to PEP, and am disappointed in the answers I've seen so far. 
One person explained that the Telebit used spoofing... which I'm sure Larry 
knows.
 
   Let me re-pose the question, clarified with respect to the technical 
background and specifics that I'd like to see (and I'm sure Larry would, too).
 
   I know full well that the Telebit gets its speed from the spoofing, but 
that was necessary because of PEP's unidirectional transmission nature. 
Spoofing adds nothing to windowed UUCP-g performance over a v.22bis (2400 bps) 
connection because (a) the ACK packets can be sent back without disturbing the 
flow of the data packets and (b) a 7-packet window takes two seconds to 
transmit at 2400 bps, giving the receiver plenty of time to ACK the oldest 
packet and allow the transmitter to continue non-stop.
 
   The question at hand is whether the full-duplex nature of V.32 extends this 
situation to 9600 bps. I know that the data packets need not be interrupted 
to send ACKs, but even a 7-packet window would take less than half a second to 
transmit at 9600 bps; it's entirely possible that the ACK packets might not 
arrive before the pending window reaches its limit, causing the transmitter to 
pause. This, of course, would prevent you from getting the maximum 
theoretically possible throughput (1100-1200 CPS on V.32, using synchronous 
framing a la MNP3 or V.42).
 
   Explicitly: Does anyone out there have throughput figures for UUCP 
protocols between two well-tuned and reasonably lightly loaded machines over 
a V.32 link?
 
   Thank you, and many apologies to those who are bored or even insulted by 
the great lenghts to which I've gone to ask a trivial question.
 
   Geoff
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