Supernet block sizes - recommendations?

Fri May 14 13:28:44 UTC 1993

> Ways to convince people to let go of a "class" B request:
> 
> Of course you have to consider the proposed subnetting scheme.  If they
> propose lots of 8-bit subnets with less than 10 hosts on them, we do
> suggest a different subnet size or in extreme cases even subnetting Cs. 
> 
> Tell them: "A scheme for classless inter-domain routing is coming.  This
> means classes will no longer be visible soon.  So why bother."

My simple argument is usually this:

Unless you are planning to have more than 255 hosts on a single subnet
(which might not be a good idea in a *lot* of cases, and can also be
offset by the 'secondary' addressing scheme of some router vendors),
a group of class C addresses is way more flexible than a class C.

Consider:

1. No more worries about 'split' subnets in wide area nets-- a definite
   problem in unforeseen  future expansion  plans. Subnet a class C on
   your wide area net and allocate other class C's at the end sites.

   This does not affect the site's routing tables (since their routers
   would have to carry all the subnets anyway). The large number of
   class C addresses is probably of more concern to ME (as a service
   provider) if I am not using CIDR.

2. No more worrying about variable length subnets, etc. Take a class C
   net, chop it up using whatever boundary wanted, and use a different
   mask for the other class C.

   Less administrative and technical headaches!!

Usually these arguments do the trick-- its a matter of technical sense
prevailing over 'I want a class B' pride.

	-vikas
	vikas at jvnc.net