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From: medin@cincsac.arc.nasa.gov (Milo S. Medin)
Newsgroups: comp.protocols.appletalk
Subject: Re: Ethernet vs LocalTalk
Message-ID: <25079@ames.arc.nasa.gov>
Date: 7 May 89 23:53:20 GMT
References: <947@draken.nada.kth.se> <29980@apple.Apple.COM> <278@suna.CMI.COM> <24837@ames.arc.nasa.gov>
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In article <947@draken.nada.kth.se>, ragge@nada.kth.se (Ragnar Sundblad) writes:

> I have had absolutely *NO PROBLEMS* coming up into this speed - and
> higher of course - using my macII with apples/3coms, ok - braindead,
> but not at all slow, ethernet controller via the nubus. There is no
> DMA, thats a drawback, but on the other hand, I might not be able to
> wait for other dma tasks to finish before it can do mine. That's one
> reason wy I sometimes prefer "doing it without dma".  The nubus can
> under certain circumstances keep up with a speed of 40Mbyte/sec, if
> you're using the block transfer facility which just a few devices
> support, but normally ~15Mbytes/sec is no problem at all. 10Mbits/sec
> (ethernet) is nothing.  What Van really did was patching a completely
> I/O- and realtime-braindead os to use one of its i/o-devices at
> 8-9Mbits/sec. That's really tricky, and any improvement of
> unix's-whatsoever is really welcome. 
...

If you have MAC-II's with 3com ethernet boards running TCP/IP between
them at 8-9 Mbits/sec, I'd love to see how you did it.  If you are 
just running some sort of blast protocol spitting out data without
doing and end-to-end delivery, that's a completely different issue.

I happen to have a SUN on my desk, but SUN didn't do a great job
on the hardware, just a good one (at least on the the system's
with the Lance on it)...  Potentially, there are a lot better platforms
than SUN's, but they work pretty well.

Streamlining any large multi-tasking OS for networking is definitely
hard work.  I am not claiming UNIX is the perfect OS; it's far from it.
My point is that there are lots of problems to deal with, and broken
hardware is one of them.  Broken software helps out a lot too.

					thanks,
					   Milo