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From: Poul-Henning Kamp <phk>
Message-Id: <199506251744.KAA28421@freefall.cdrom.com>
Subject: Re: FreeBSD as a router
To: dennis@et.htp.com (dennis)
Date: Sun, 25 Jun 1995 10:44:22 -0700 (PDT)
Cc: freebsd-hackers@freebsd.org
In-Reply-To: <199506251650.MAA26983@mail.htp.com> from "dennis" at Jun 25, 95 12:50:53 pm
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> >> for the full frame to arrive, which was what we were talking about) , which
> >> means that net throughput cannot be greater than 50% of 10mbs.
> >> 
> >
> >Why shouldn't I be able to receive the next frame while transmitting the 
> >first one ?
> >
> >Recv Frame 1  Recv Frame 2  Recv Frame 3
> >------------> ------------> ------------>
> >	      Send Frame 1  Send Frame 2 ...
> >
> 
> It has nothing to do with receiving while transmitting, it has to do with
> physical science.
> 
> Box A ----> Box B (the Ethernet Router) -----> Box C
> 
> I transmit a frame from Box A to Box B. For simplicity say it takes 100
> microseconds to get  to point B at 10mbs. I now need to re-transmit the
> frame to get it to Box C. It takes ANOTHER 100 microseconds to get it to Box
> C (Assuming no latency). To get from Box A to Box C with a non-specialized
> controller takes 200 microseconds, or 1/2 the single medium's max throughput.

Dennis, you are right if we substitute "latency" for "thoughput".

Now if you used to be a dinosaur keeper in an SNA network, I can understand
the confusion, since SNA, being the mess it is, has a close tie between the
two metrics.  But no other protocol (except XMODEM, which hardly qualifies
as a protocol) has used non-windowed flowcontrol in recent times.

No matter what, I award you a third conical hat <<<-:) and suggest you go 
read a text-book on data communications before you open your big mouth on 
this subject again.  (I can recommend Tannembaums book on the subject.)

-- 
Poul-Henning Kamp           | phk@FreeBSD.ORG       FreeBSD Core-team.
http://www.freebsd.org/~phk | phk@login.dknet.dk    Private mailbox.
whois: [PHK]                | phk@ref.tfs.com       TRW Financial Systems, Inc.
Just that: dried leaves in boiling water ?