Date: Fri, 27 Feb 1998 00:41:04 +0100 From: sthaug@nethelp.no To: dlittell@onramp.net Cc: hackers@FreeBSD.ORG Subject: Re: Token Ring for FreeBSD yet? Message-ID: <27882.888536464@verdi.nethelp.no> In-Reply-To: Your message of "Wed, 25 Feb 1998 19:27:09 -0600" References: <34F4C4ED.31DFF4F5@onramp.net>
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> > Sorry, it's not that simple. On a token ring network, tokens can get lost. > > Yes, this happens in real life. So any "guarantee" that you give for token > > ring networks is based on statistics. > > Yeah, it really is that simple. Token loss recovery time has an upper > bound Yes. So does the waiting time for Ethernet with maximum number of collisions (367 ms). Think about what happens: In *both* cases higher protocol layers will most likely see a timeout and perform a retransmit in software. Thus, either they are both deterministic (time to transmit has an upper bound), or neither of them are. > and token ring-based networks degrade gracefully, ensuring some > non-zero throughput even at 100% offered load. I believe there are > meltdown scenarios in Ethernet that guarantee you'll never get anything > out. The "meltdown scenarios" are as far as I know based on infinite number of stations, which is specifically disallowed by the Ethernet rules. There is a *reason* for the limit of maximum 1024 stations per collision domain - it is precisely to avoid such a meltdown. The "meltdown scenarios" have been debunked both by theory and practical measurements by now. There is no reason to drag them out again. Steinar Haug, Nethelp consulting, sthaug@nethelp.no To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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