Re: [dae%psuvax1.bitnet@jade.Berkeley.E


jon@Cs.Ucl.AC.UK
Tue, 24 Mar 87 12:10:52 WET


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From: "Dennis G. Perry" <From: "Dennis G. Perry" <PERRY@mil.darpa.vax>
Subject: Re: [dae%psuvax1.bitnet@jade.Berkeley.EDU: Network horror story]
To: To: LYNCH@edu.isi.a
Cc: Cc: PERRY@mil.darpa.vax, Cc: PERRY@mil.darpa.vax, TCP-IP@arpa.sri-nic, Cc: PERRY@mil.darpa.vax, TCP-IP@arpa.sri-nic, perry@mil.darpa.vax
Message-Id: <VAX-MM(195)+TOPSLIB(124) 23-Mar-87 07:15:18.VAX.DARPA.MIL>
In-Reply-To: Message from "Dan Lynch <LYNCH@A.ISI.EDU>" of 22 Mar 1987 19:25:30 EST

Dan, not sure there has been any model, or any great research either.

dennis
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If you look at the original Internet design issues, the idea of
fate sharing and a tactical network, and
so on, determined gateway/routers were connectionless.

A bit like the old CSMA versus token arguments, in a WAN context,
the consequence of this design decision is
that (without resource reservation a la
X.25) you HAVE to over-engineer for bandwidth and delay, or it
just doesn't work.

Witness the UK Academic X.25 network availability under extreme
load is 99% plus, with MTTR in the minutes, and MTBFs in the
days range, compared with the Internet under extreme load,
where we were seeing availabilities of 20-30% and MTTRs of
hours and MTBFs in the hour range.

I look forward to seeing some intermediate scheme
("connectionish networks") for the tactical+low-congestion
internet.

Jon



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