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From: marc@aria.ascend.com (Marco S Hyman)
Newsgroups: comp.dcom.modems
Subject: Re: Uses of V.42 (bis?) data compression
Message-ID: <529@aria.ascend.com>
Date: 13 Apr 91 19:07:41 GMT
References: <10334@pitt.UUCP> <3908.280363d4@hayes.uucp> <1991Apr12.132116.11546@hobbit.gandalf.ca>
Distribution: na
Organization: Ascend Communications -- San Francisco
Lines: 21

In article <1991Apr12.132116.11546@hobbit.gandalf.ca> dcarr@hobbit.gandalf.ca (Dave Carr) writes:
 > I don't see this at all.  Perhaps the link level protocol.
 > Perhaps the line error rate.  But the compression should be
 > independant on the carrier speed. 

Dave, how would you feel if you kept putting bytes into one end of a data link
and nothing came out the other end?  Why?  Because the first end can still do
some more compression on the data and doesn't have a new symbol to send.
Compression efficiency is only half the problem -- you want to keep your
bandwidth filled.  What's the use of compressing more while the bandwidth sits
idle.  When the (very) efficient compression symbol is finally sent there is
even more delay added to output the cleartext at DTE interface speeds. All
The only result of making compression independant of the carrier speed is
increased response time.

Throughput is not the only factor in communcations links -- you can never
forget about response time.
-- 
// marc
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