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Date:      Tue, 06 Oct 1998 23:49:33 -0600
From:      Warner Losh <imp@village.org>
To:        Peter Wemm <peter@netplex.com.au>
Cc:        Marc Slemko <marcs@znep.com>, Nate Williams <nate@mt.sri.com>, Zach Heilig <zach@gaffaneys.com>, Kris Kennaway <kkennawa@physics.adelaide.edu.au>, current@FreeBSD.ORG
Subject:   Re: fetch -p 
Message-ID:  <199810070549.XAA13020@harmony.village.org>
In-Reply-To: Your message of "Sat, 03 Oct 1998 01:08:39 %2B0800." <199810021708.BAA24001@spinner.netplex.com.au> 
References:  <199810021708.BAA24001@spinner.netplex.com.au>  

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In message <199810021708.BAA24001@spinner.netplex.com.au> Peter Wemm writes:
: It's similar to ISDN.  There, a 64K B channel is 64000 bits/sec on the
: wire.  Data is synchronous and clock synchronized so there are no start and
: stop bits, just bit patterns for start and end of packets etc.  This means
: that your 64K link gives you 8000 (theoretical) bytes/sec.  There are
: losses because the HDLC frames have address/control data, CRC's, start
: markers, packet length (I think). So, in reality you get a smidge less than
: 8000 bytes/sec when you are using large packets.

HDLC also requires bit stuffing which can cuase slighly lower data
rates too.  But that is slight is very slight indeed (only needed for
6 or 7 consecutive 1 bits, iirc).

Warner

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