*BSD News Article 83056


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From: cjs@cynic.portal.ca (Curt Sampson)
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 12:52:20 -0800
Organization: Internet Portal Services, Inc.
Lines: 33
Message-ID: <56l9i4$e7k@cynic.portal.ca>
References: <56cfhc$h8b@access5.digex.net> <56d1m9$9ba@server05.icaen.uiowa.edu> <56dl8p$rje@panix2.panix.com> <56igd8$if@anorak.coverform.lan>
NNTP-Posting-Host: cynic.portal.ca
Xref: euryale.cc.adfa.oz.au comp.unix.admin:50532 comp.protocols.ppp:15922 comp.unix.questions:91421 comp.unix.bsd.freebsd.misc:31145 comp.unix.bsd.netbsd.misc:4875

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.