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From: ron@brl-smoke.ARPA (Ron Natalie <ron>)
Newsgroups: net.dcom
Subject: Re: What is TCP/IP Subnetting?
Message-ID: <649@brl-smoke.ARPA>
Date: Tue, 28-Jan-86 01:14:26 EST
Article-I.D.: brl-smok.649
Posted: Tue Jan 28 01:14:26 1986
Date-Received: Thu, 30-Jan-86 01:14:24 EST
References: <904@rlgvax.UUCP> <8900008@uiucdcs>
Organization: Ballistic Research Lab
Lines: 37

> 
>  [CUTE PICTURE ENCLOSED]
> 							      
> The advantage of the subnet, it keeps the diskless Suns traffic
> and work stations off of the main net, except when grabbing a file
> from a server or sending output to the printer, etc.
> 
> Also, if one of the subnets fail, open coax, bad transceiver, etc.,
> it will not hang the other nets at a different gateway level. All levels
> can access the printer, rlogins can get the work stations to main frame
> to check mail, etc.
> 
> Note that the gateway machines require two ethernet interfaces each
> in the above illustration.
> 
> Hope this helps. I think this is the application of the term as you
> are using it.

Actually, none of this are points for subnetting.  What he is showing
is why you don't want your entire plant to be one net.  IP subnetting
is simply the practice of using a single IP network number across
multiple physical nets.  The advantage is that outside your
organization, noone need know about the topology of your local
configuration, they see a single IP netork number referencing an
apparent single network. The trick is that within one subnet has to
realize that some of the hosts with the same network number are on
different nets.

Essentially, the idea is that people rarely have more than 256 hosts
supported by single class C net number, but frequently have multiple
nets.  There is no reason to burden the rest of the internet system
with a mutliple net numbers that each refer to a handful of hosts in
the same system when you can do the work locally and divide up a single
network nubmer.  A plan for subnetting is available as an RFC from the
NIC.  The 4.3 BSD release will support this.

-Ron