tcpip - How can I add more than 255 machines to a single Class C network?

I'm mainly a programmer. I have no idea beyond some basic theory when it comes to Networking/Administrating.

My university feels that we should course at least the basics in Networking and I'm psyched. It's something incredibly new to me and I'm enjoying the class a lot.

Yesterday was my first day and he posed the following question.

"Since each C-level network can only have a maximum of 254 IP addresses, how could you add 300 machines to a single C-level network?

I was thinking something like:

192.168.1.1 
192.168.1.2 
192.168.1.3
---
192.168.1.254 (Make this a ROUTER)

    //and inside this router's network I could repeat the following addresses no problem.
    192.168.1.1
    192.168.1.2
    //etc.

Is this what my teacher was talking about? My teacher said this has a special name and we should research what it was called.

Anyone care to share some knowledge? :)

Edit: Maybe I'm not expressing my question clear enough; I need to have 300 machines all being able to communicate with each other, and all of them being within the same C-level network. (This is a deprecated term you say, what is it called now?)

How could I write this solution down on paper, explaining what I need?

Answer

I'm fairly certain that the concept your teacher is pointing you towards is NAT (Network Address Translation). It's a function performed by a router which allows a (usually private) network to share a (usually public) IP address. This is one of the primary functions of any off the shelf router you use to connect a home network to an Internet connection.

In your example, you cannot repeat usage of the same subnet on the "internal" network.

A brief explanation, given the following configuration:

192.168.1.0/24
|
192.168.1.1 (external interface)
Router performing NAT
192.168.2.1 (internal interface)
|
192.168.2.0/24

The router performing NAT would have hosts behind it on a different subnet (notice the "2" in the 3rd octet). The hosts in the 192.168.2.0/24 network would set the NAT router (192.168.2.1) as their gateway.

When traffic flows through the router, the NAT function "translates" the IP headers, changing the source address to it's own "external" IP (192.168.1.1) and forwards the traffic along. It then keeps a table of connection entries, so when the return traffic arrives, it reverses the translation it performed and forwards the reply back to the original sender on the "internal" network.

http://en.wikipedia.org/wiki/Network_address_translation