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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.unix
Subject: Re: rts/cts - a tutorial on flow control
Message-ID: <6098@umcp-cs.UUCP>
Date: Sun, 26-May-85 14:58:36 EDT
Article-I.D.: umcp-cs.6098
Posted: Sun May 26 14:58:36 1985
Date-Received: Mon, 27-May-85 07:30:38 EDT
References: <5620@utzoo.UUCP> <79@decvax.UUCP>
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 22

> The "negative" flow-control methods work (XOFF/XON) work satisfactorily
> if sufficient space is allocated for overrun.

True, but unfortunately, the amount of space that is sufficient has
recently gone way up...

> For example, (assuming 9600 Baud transmission)

And no end-to-end network delays!

> the receiver can allocate a 400 byte buffer, sending XOFF when there
> are 100 bytes unprocessed bytes in the terminal input buffer.  This
> gives the host about 600 msec. to stop output.

That's assuming the XOFF makes it from the stopper to the stoppee
without delay; untrue in general, now.  (If you gave yourself sufficient
buffering to handle up to 30 seconds of delay, I suppose I'd call
that sufficient: no one would want to wait longer for echo . . . .)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)
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