[MLB-WIRELESS] IP address range for Geelong?

[Adrian Close]

On Tue, 12 Feb 2002, Will Lotto wrote:

> People really shouldn't be using 10.0.0.0 addresses for their private
> networks... It's class A. How many private networks have a need for a
> class A subnet?

You're missing some bits of the picture...

(I find it strangely fitting that net 10 was the old ARPA network.)

Classful allocation and routing went out of fashion quite a while ago.
The new thing is called CIDR (Classless Inter Domain Routing) and is quite
popular.  See RFC 1519 (e.g. http://www.faqs.org/rfcs/rfc1519.html).

People still refer to Class A, B and C networks, but only for convenience.
They can also be referred to as /8, /16 and /24 networks, those numbers
being the number of consecutive binary bits used in the "netmask" to
specify each (in decimal, 255.0.0.0, 255.255.0.0 and 255.255.255.0).

One of the really powerful things with CIDR is the ability to aggregate
multiple networks into single routing announcements.

There's nothing wrong with a /23 (two Class C's or /24's together) or a
/19, for example.  A /32 specifies exactly one network address (all bits
used for network).  A /31, two addresses.  A /30, four addresses... and so
on...

About the only thing you can't do with CIDR notation is specify a
discontiguous network, but that's not often required.  ;)

Adrian.


--
To unsubscribe, send mail to minordomo at wireless.org.au with a subject of 'unsubscribe melbwireless'  
Archive at: http://www.wireless.org.au/cgi-bin/minorweb.pl?A=LIST&L=melbwireless
IRC at: au.austnet.org #melb-wireless