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From: kline@tera.com (Gary Kline)
Message-Id: <9601171721.AA01331@tera.com>
Subject: Re: delays in ppp solved
To: wes@intele.net (Barnacle Wes)
Date: Wed, 17 Jan 1996 09:21:47 -0800 (PST)
Cc: jmb@freebsd.org, questions@freebsd.org
In-Reply-To: <199601171517.IAA00439@intele.net> from "Barnacle Wes" at Jan 17, 96 08:17:47 am
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According to Barnacle Wes:
> 
> On Tue, 16 Jan 1996, Barnacle Wes wrote:
> % 2. Modem compression often interferes with, and lengthens transfer of,
> %    compressed files such as .gz and .jpg.
> 
> > 	this is indicative of a cheesy modem.  LZW with the BT (british 
> > telecom) extentions will not expand the data.  modem compression frees 
> > your processor for other tasks, letting the modem do some of the work (of 
> > course the cost here is more bytes thru the serial port since the modem 
> > un/compresses the data.  could be a problem for cheesy uarts or chessy 
> > clones of decent uarts)
> 
> Even cheese-less modems will cause some delay, as they have to pause
> and accumulate enough of the incoming data stream to determine that
> compression won't be effective.  Since this process is re-started
> each time the communications "turn around", i.e. at each window turn
> for ftp, these small pauses add up over a long transfer.
> 

	So, what's the bottom line, Gentlemen?  Should
	I disable compression with my user-ppp; and how?

	A few days back I ftp'd back a *.zip file and my USR 28.8
	gave me a comparitively good 3.2Kbps rate.  The ``CS'' LED
	flashed on the modem.  (I don't know why... )   I tested 
	the transfer rate with the same file compressed with gzip.
	The CS light was steady and the transfer rate fell to 2.9K.

	To me this could mean that the EEPROM in the modem recognized
	the *.zip compression and let it through.   And it wasn't
	intelligent enough to recognize the *.gz compression.

	Or??


	gary kline