Question : Supernetting

I am studying for the MCSE and I am trying to figure out supernetting. I have a good handle on subnetting but I need a better, clearer explanation than my book provides. Please give an example.

Answer : Supernetting

Please forgive my previous comment. I realized it would cause more confusion than assistance. Chauk it up to jet lag (the effect where body lands, but the brain is at 30k feet).

OK here goes:

Lets say you have an InterNic assigned address in the class c range of: 200.200.200.200

You need more, but nothing near the capablity of a "B" address (assuming you could get one).

You would NEED to get an address that is either above or below your current one. To make the point, lets say you need more than what two Class C address can give you, so you apply for Three addresses, total.

you would have to have 200.200.200.199
you had                200.200.200.200
and the third hads tobe200.200.200.201

Forget one of them if you don't need three.

The major point here is you have in binary, a continous range
between either the 199 to the 200 octet, or between the 200 and the 201 or all three 199-200-200 are for binary purposes, without a break.

Given that, you can start moving the binary masks of your subnet TOWARD the host id. (that is what my brain was thinking in my previous comment, but the fingers and brain we're connected yet).

It may help to break your subnet mask into binary. When you do that, also break out the IP address into binary, directly above the subnet mask. Keep a one to one relationship between the binary ranges of IP and sub net mask.

Once drawn out, look at the 1's in your subnet mask. Think of them as a Pipe || <-(that's a 1 as a pipe)  The pipe allows the NET ID flow through the pipe.   Now look at the 0' (zeros) in your subnet mask. Think of them as a barrel or a sponge that absorbes the IP address, preventing them to be used as net address, and that makes them available for host id's.
you will notice that all valid subnets have all the pipes then all the sponges. Not possible to mix pipes and sponges in a even or odd order.  Kinda of like a digital segeration movement. "All you ones'(pipes) on the left. Hey sponges! (zero's) on the right side of the octet bus!"

With a contigous order, you can fiddle with pipes and sponges, because you have a contigous order between the natural breaks in the Class range, so, you can ingore the fact your jumping an IP address, 'cause its yours. In effect, its a bigger than C ranged IP address, cause you got two or more addresses, all butted up against each other.......

Got it?