The Classed/Classless IP Thing

Posted by: mindful webworker in perpetual amazement at April 28, 2016 12:54 AM (5a8XA)

Sorry about the lack of response earlier on the classed/classless IP thing. I was getting ready for work and didn't think to check back. In case you check back, I'll try to explain it.

Basically, early in the days of the internet, IANA, the organization that was formed to keep IP addresses sorted, would give out addresses in job lots with what was called a class license. The Class A licenses gave you about 16 million addresses, Class B's gave you 65,534, and Class C gave you 254. The exact numbers were due to the magic of binary numbers. Unfortunately, this was extremely inconvenient.

Not only was IANA not careful about how they handed out the class licenses, but they were also in inconvenient sizes for real-world users. Suppose you're an ISP with 2 million subscribers. Do you get 1 Class A, or a whole bunch of Class B's? Most of them got a single Class A, and let the unused addresses go to waste... and since IP addresses are now a precious resource, they guard their class licenses jealously and refuse to trade.

IPv6 does away with that. No more class licenses, every device generates a much longer, unique address that's based on your regional backbone servers, your ISP, and your network card's MAC address, and there's such a ridiculous amount of combinations that we'll (hopefully) never use them, or they'll have to do something that has an even more ungodly amount of possible combinations...