[2236] in Commercialization & Privatization of the Internet
SLIPing Questions and Answers
daemon@ATHENA.MIT.EDU (Barry Shein)
Sat Feb 1 23:21:13 1992
Date: Sat, 1 Feb 92 23:17:21 -0500
From: bzs@world.std.com (Barry Shein)
To: cook@tmn.com
Cc: com-priv@psi.com
In-Reply-To: Gordon Cook's message of 1 Feb 92 22:05:10 EST (Sat) <9202012205.AA17453@tmn.com>
There are boxes like the Telebit NetBlazer which make it pretty easy
to introduce SLIP at a low-cost: Around $3K for a standalone little
box with a serial/modem plug and an ethernet plug. Once configured,
the rest of the hosts on the net are oblivious to how this is being
accomplished, they just need TCP/IP and the knowledge that there's
this router out there that can get anywhere.
But my question was more like: What problem are we solving with SLIP?
SLIP tends to be used on either dial-up or dedicated 9600b (or
thereabouts) circuits, low-speed. These tend to be the choice of
individual or very small group users, home, small business, etc.
A lot of the low-end issues being raised here are actually addressing
relatively large groups of people, public schools, libraries etc.
Other than someone saying "9600b SLIP is better than nothing!", SLIP
is probably not the right solution for such applications: It's too
slow for more than one or a very few people and tends towards metered
usage models (e.g. SLIP over POTS.)
I proposed a model which minimizes administration and could support
around 32 simultaneous sessions (depending on what's actually being
done) for a relatively low price, by using terminal servers across
56kb lines. It could be easily duplicated for N*32 seats. But it
didn't involve any SLIP. Local hardware and administration is
minimized.
Now, you could run SLIP into those terminal servers, but then you have
the whole she-bang of administration and configuration out at the
site.
For example, finding and configuring and caring for TCP/IP for 32 PC's
or Macs. People who brush that off as trivial are not being realistic.
Terminal emulation packages *are* easy to set up and maintain.
More important: What is the SLIP out to the site really getting you?
Are you going to run a mail server at the site? What does that entail?
Netnews? Backups of critical software and data? Installation of new
software versions for all of the above???
This is where the notion of a somewhat centralized administration
becomes attractive. All the end-users have to do is open a terminal
emulation window to a site which is maintained, fixed, backed up, etc.
I have done this sort of thing at large sites for over a decade
(Harvard, Boston U, here on World), I have some idea about what the
problems are.
We lost a disk during USENIX last week and managed to blow about 8
hours putting it all back together, and I'm damned good at what I do.
Is that the kind of thing we expect to go on in libraries and public
schools???
*I* wouldn't want their lives to be much more complicated than "oops,
this floppy is bad, hand me that one over there."
The beauty of networking is location transparency, that's what you
want to strive for, who cares exactly how that's accomplished? Put
another way, do you want own and run a telephone or a 5ESS? Most
people just want a telephone that can ACCESS a 5ESS which someone else
worries about.
You don't build large systems based on what can go right. You build
large systems based on what can go WRONG. The "right" part is easy,
any fool can use a system which is working properly.
So my comment was generated by the feeling that we're confusing two
different needs, hence my plaint: "What's the question?"
SLIP tends to be the INDIVIDUAL's (or very small group) solution.
As Richard Mandelbaum pointed out, NYC has 1M students in its public
schools. That's anywhere from 500 to 5000* students per site. I doubt
SLIP is an effective solution for applications like that in most
cases.
Even a small school or library district serves hundreds to thousands
of people, and probably needs on the order of 32 seats per site.
* I went to Martin Van Buren High School in Queens, there were about
5,000 students there in 1969, I assume it's still about the same. P.S.
115, my elementary school, probably had closer to 500, but I couldn't
count that high back then :-)
-Barry Shein
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