🚀 go-pugleaf

In article <7644@goofy.Apple.COM> escher@Apple.COM I write:
>In article <793@thebeach.UUCP> rich@cfi.COM () writes:
>
>The subnet mask tells the host what part of the adress to use for
>the net+subnet pair.  Note that you can set it on any bit -- you
>can subnet class C addresses, so you could have two networks with
>127 hosts each.
>

I made a mistake here... apparently the subnet mask must be at least two
bits past the net number.  Thus you may have up to four subnets of 64 hosts
each on a class C net, but not two nets of 127 hosts each.  Or 62 hosts,
rather: don't use all 1's for the host number, that is the broadcast address;
all 0's sometimes means the net itself, and is used as the broadcast
address (incorrectly!) by BSD 4.2 Unix systems.

Note that your broadcast address will be all 1's in the host part only, and
not in the (subnet, host) part.  MacTCP takes care of this itself, but A/UX
has you set it manually.  When I installed an A/UX router, I was used to the
idea that one would only set the subnet at a byte boundary, where Apple
uses 10 bits for its subnet mask.  Thus, I was addressing all my broadcasts to
host 256 on my subnet.  Fortunately, no one was there to receive them.

Note that it is also important to have a unique address.  Someone was in
a hurry to set up PC-NFS when I was out of the office, so someone just told
him to "Pick a high number.  It's not likely to be used."  When I got back in
there was an urgent message from the person whose number he had picked, and
one from him saying he could not get PC-NFS installed!

If you have a big site, where it is to slow, or inconvenient to have a single
administrator hand out all the addresses, assign an administrator for each
subnet, and have her hand out the addresses.  If even this is unsatisfactory,
have each manager assigned a range of addresses on the net, so assign to her
employees as they need them.  In any case, set up a quick convenient scheme
for people to get their addresses, so they won't try just guessing one!
-- 
Michael D. Crawford
Oddball Enterprises
606 Modesto Avenue
Santa Cruz, CA 95060
oddball!mike@ucscc.ucsc.edu

Consulting for Apple Computer Inc.
escher@apple.com
Applelink: escher@apple.com@INTERNET#

The opinions expressed here are solely my own.