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From: dillon@flea.best.net (Matt Dillon)
Newsgroups: comp.unix.admin,comp.protocols.ppp,comp.unix.questions,comp.unix.bsd.freebsd.misc,comp.unix.bsd.netbsd.misc
Subject: Re: Best Unix for SLIP/PPP Server- Best Reliability/Cost?
Date: 16 Nov 1996 21:30:01 GMT
Organization: BEST Internet Communications, Inc.
Lines: 46
Message-ID: <56lbop$egq@nntp1.best.com>
References: <56cfhc$h8b@access5.digex.net> <56dl8p$rje@panix2.panix.com> <56igd8$if@anorak.coverform.lan> <56l9i4$e7k@cynic.portal.ca>
NNTP-Posting-Host: flea.best.net
Xref: euryale.cc.adfa.oz.au comp.unix.admin:50498 comp.protocols.ppp:15909 comp.unix.questions:91376 comp.unix.bsd.freebsd.misc:31101 comp.unix.bsd.netbsd.misc:4864
:In article <56l9i4$e7k@cynic.portal.ca>,
:Curt Sampson <cjs@cynic.portal.ca> wrote:
:>In article <56igd8$if@anorak.coverform.lan>,
:>Brian Somers <brian%anorak.coverform.lan@awfulhak.demon.co.uk> wrote:
:>
:>>: The real question is how many serial ports he can put in a PC before
:>>: the thing has such a tremendous interrupt load that it can't get anything
:>>: else done.
:>>...
:>>Even if you have one IRQ for 16 ports, you're only really looking at 80
:>>direct serial connections per pc.
:>
:>Putting hundreds of serial ports on a PC is not a problem. There
:>are various manufacturers out there making single-board products
:>that will handle well over a hundred serial ports, and you can
:>easily put several of these boards in a system. However, a thousand
:>on a single PC is likely pushing it a bit.
:>
:>Interrupts are not a problem when you have this many serial ports,
:>since there are none: you poll.
:>
:>I've personally seen a 486/66 handle about 70 serial ports at 14.4
:>with no problem, and a Pentium handle 150 at 28.8 with no problem.
:>These were running SCO Unix with Digiboards and a custom bulletin-board
:>application.
:>
:>But still, before you go ahead with something like this, you should
:>keep in mind the fact that this applicaton was eventually moved to
:>terminal servers too.
:>
:>cjs
:>--
:>Curt Sampson cjs@portal.ca Info at http://www.portal.ca/
:>Internet Portal Services, Inc.
:>Vancouver, BC (604) 257-9400 De gustibus, aut bene aut nihil.
Nobody polls serial ports except old Mac software that didn't know
any better.
Modern multi-port serial cards will do hardware handshaking themselves
and use FIFOs. A PC would generally have no problem handling a hundred
ports. A pentium could probably run PPP with three or four hundred
(at 115.2Kbps) before it gets saturated, assuming you dedicated it
entirely to the task.
-Matt