What's the point of subnet?

[muno]

At school (I study at evenings), we've been learning on how to subnet public ip addresses.

I can calculate the stuff pretty easily now, but I still don't grasp the idea what it's used for.

So, my question is, what is it used for? Where would I probably need to subnet computers and why?

What's the advantage of subnetting over nat?
-M

[DVNT1]

Why subnet? To reduce the potentially unused IP addresses when allocating IP to an entity. Without subnetting every IP allocation would be in blocks of 65k IPs. So every allocation of 65k would have huge amounts of wasted IP addresses except for the largest of networks.

The default subnets for the different classes (A, B, C) help some but still many small/med. business won't need 254 public IP addresses so more subnetting variations are done.

You will indirectly work with subnetting anytime you work with public IP address, especially if you work with routers. You may not ever do the actual subnet planning unless you are requestiing IP addresses from ICANN or otherwise working with large networks.

NAT plays a different role then subnets. Even sites with NAT may still deal with subnets on the public side and even the internal side. NAT also doesn't work well with every application (one example is IPSEC).

Sorry so brief but I'm off to work. Please ask for more examples and clarifications if it would help!

[muno]

Yes, I was waiting for your reply
Your knowledge on networks is astonishing.

Please provide an example on how it is used, and clarify more, when you have time

I didn't quite understand anything
-M

[no1_vern]

Check out this page, maybe it'll help you.

http://216.239.41.104/search?q=cache...hl=en&ie=UTF-8

[muno]

Heh, who's 'portmaster'?
That link didn't quite explain (from what I understood) what I'm asking. Or if it did, I just didn't understand the part I should've understood.
-M

[no1_vern]

Sorry,
A "portmaster" is a remote access concentrator(basically a server that supports remote personnel usually having a full range of connections, from analog modem, to T1/E1 and ISDN. It allows several people to access your network remotely. I should have said that when I posted the link.