Date: Sun, 25 Jun 1995 10:44:22 -0700 (PDT) From: Poul-Henning Kamp <phk> To: dennis@et.htp.com (dennis) Cc: freebsd-hackers@freebsd.org Subject: Re: FreeBSD as a router Message-ID: <199506251744.KAA28421@freefall.cdrom.com> 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 ?
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