Path: utzoo!mnetor!uunet!husc6!mailrus!ames!pasteur!ucbvax!UM.CC.UMICH.EDU!Doug_Nelson
From: Doug_Nelson@UM.CC.UMICH.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Subnetting
Message-ID: <3026964@um.cc.umich.edu>
Date: 7 May 88 15:11:58 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 26

In message <1607@erix.UUCP>, Per Hedeland writes:
 
>  a) It appears that the intended use of subnetting assumes that all the "subs"
>     of a "whole" net are interconnected, i.e. the backbone and the client
>     segments in our case should be "subs" of the same "whole" - in particular,
>     "automatic" routing by means of routed (which we desire) will not work
>     otherwise, as far as I can understand.
 
Yes, that has to be true - you can only advertise your full network,
not your subnets, to the Internet at large.
 
>  b) "Subs" of a given "whole" must be of equal size.
 
This is a mistaken assumption.  There is nothing that prevents you
from using subnets of different sizes on a given net, except for
software that isn't up to speed on subnetting (notably SunOS 3.x).
For example, our campus-wide network is a class B sized subnet of a
class A network.  The Merit network itself is a class A/2 subnet, and
Univ of Michigan has parceled out a number of class C-sized subnets.
I plan to pass out class C-sized subnets of our network (or possibly
smaller) to several other campus Ethernets, as soon as we get SunOS
4.0 installed.
 
Doug Nelson                   den@serv1.cl.msu.edu
Michigan State University     08071den@msu.bitnet
Computer Laboratory