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Xref: sserve comp.os.386bsd.questions:16966 comp.os.386bsd.development:3288 Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!bunyip.cc.uq.oz.au!munnari.oz.au!news.hawaii.edu!ames!elroy.jpl.nasa.gov!decwrl!vixie!nnrp!paul From: paul@vix.com (Paul A Vixie) Newsgroups: comp.os.386bsd.questions,comp.os.386bsd.development Subject: correction (Re: ethernet throughput) Date: 1 Mar 95 03:02:33 Organization: Vixie Enterprises Lines: 26 Message-ID: <PAUL.95Mar1030233@sager.vix.com> References: <3it7m8$o39@clavin.uprc.com> <3itrg4$pfj@crl9.crl.com> NNTP-Posting-Host: sager.home.vix.com In-reply-to: ggrant@crl.com's message of 27 Feb 1995 16:41:40 -0800 >in reality , due to CS/MA gaussian backoff, a normal ethernet cable >saturates at about 3.5 Megabits per second... or 450-500 KBytes per second.. Not even close. Boggs and Mogul at DECWRL published a tech report back in 1988 that showed an ethernet that gracefully load shared for up to 30 hosts (DECWRL Titans, early RISC machines) such that a fair share was still given (roughly 1/N to each of N hosts) and that the aggregate data rate for N hosts was in the 90+% range even with 30 hosts banging away at full speed). In my own less ambitious test environment (driver development for BSD/OS), I regularly get 1150KB/s TCP throughput between two mediocre PC hosts using cheap $100 3COM cards with tiny 2K FIFO's. That's the theoretical maximum for a collision free ethernet, which mine was that day. Now, I don't know what would happen if I put 30 of my cheap PC's on a wire (and I never shall know, either), but after helping Boggs and Mogul set up their test net and after reading their tech report, I am a strong believer in Ethernet. <wrl-techreports@decwrl.dec.com> is a mailbot which can be coerced into sending you postscript for the Boggs/Mogul report if you ask it for "help". Disclaimer: I don't work for DEC any more. -- Paul Vixie La Honda, CA <paul@vix.com> decwrl!vixie!paul