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Date:      Wed, 25 Feb 1998 19:27:09 -0600
From:      Dave Littell <dlittell@onramp.net>
To:        hackers@FreeBSD.ORG
Subject:   Re: Token Ring for FreeBSD yet?
Message-ID:  <34F4C4ED.31DFF4F5@onramp.net>
References:  <Pine.BSF.3.96.980224224016.306A-100000@duey.hs.wolves.k12.mo.us> <14181.888392839@verdi.nethelp.no>

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sthaug@nethelp.no wrote:
> 
> > For example, can you guarantee,
> > mathematically, that you can get a given mount of data across the network
> > in a given amount of time, worst-case?  Can't do that with Ethernet, since
> > it works too chaotically.  In token-passing and polling based networks,
> > you can say with certainty that even under maximum load, you can get a
> > packet from one machine to another in X milliseconds.
> 
> 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 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.

Dave

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