Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!iconsys!caeco!i-core!geo-works!bryan
From: bryan@geo-works.UUCP (Bryan Ford)
Newsgroups: comp.sys.amiga
Subject: Re: Software-only network protocol standards
Message-ID: <1719.AA1719@geo-works>
Date: 14 Jul 89 10:48:18 GMT
References: <1089@sas.UUCP>
Lines: 40

In article <1089@sas.UUCP>, walker@sas.UUCP (Doug Walker) said:
>What's the matter with DNET?  Seems to be a perfectly workable network protocol
>standard over serial lines.  Write a few DNET servers, and you can do anything.

First, DNET was built as a two-computer network, and what I'm doing
requires that you can hook up many computers in a mesh-type network just by
using standard null-modem cables.  Of course, you could just add relay
servers and things like that, but there are problems with that explained
below.

DNET is written completely in C, and doesn't have enough OSI layering built
into the code to make it easy to convert part to assembly language.  When
you're running at over 200KBPS, something in C just can't cut it.  And,
even if the low-level parts were rewritten, the relay servers would still
basically be way on top in the Application layer, in a different process no
less, when they're supposed to be way down in the Network layer.  As a
result, to just relay a packet, DNET has to do a bunch of message-passing
stuff to get the packet to the relay server, then the server sends a
possibly modified version of the packet back to DNET, which then sends the
packet to another server.  Though the Amiga's message-passing system is
very efficient, they're just not efficient *enough* for this.

The protocol was not written for high-speed relaying.  It requires that
each packet be gotten entirely and correctly by one machine before it sends
it off to the next.  To get really good speed, you've got to relay each
*byte* as soon as it is received, then do your checking later.

Please note that this isn't a flame against DNET or Matt Dillon, and I
think it's a wondeful program.  It's just not right for my purpose.

Any discussion?

				Bryan

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