Wednesday, February 2, 2011

IPv4 Exhaustion: Feb 1, 2011

The Internet has used Internet Protocol version 4 for decades, with addresses like But those addresses are only 32 bits long, so there are only 4 billion of them. And they are running out. They are managed by IANA, which distributes addresses to the five Regional Internet Registries (RIRs), who in turn distribute them to companies and Internet Service Providers.

On Feb 1, 2011, IANA distributed the last IPv4 blocks to RIRs. No more new IPv4 addresses will ever be available. The RIRs will be more stingy in distributing the last addresses, also. ARIN, the RIR servicing the USA, will soon require recipients of new IPv4 addresses to demonstrate progress in IPv6 deployment first. The five RIRs will each run out of IPv4 addresses at different times, as shown in this chart:

In 2012, after ARIN runs out of IPv4 addresses, it will be impossible to connect new devices over IPv4 directly to the Internet with fresh addresses. Companies will either have to use IPv6, or purchase used IP addresses from smarter people who already converted to IPv6. CCSF has 65,536 IPv4 addresses, and I want to sell them for $1 million. I just got my first serious offer to buy them yesterday, but they might not meet my price yet. The campus administration may be unwilling to sell, but I think when the price gets high enough, they will become convinced.

IPv6 uses 128-bit addresses like 2607:F128:42:a8::2. There are 340 billion billion billion billion of them, so we won't run out of them any time soon.

IPv4 will continue to be the dominant Internet Protocol for several more years, but it will gradually become disused, like black-and-white television. For the next decade, all network professionals will need to understand, deploy, and support both IPv4 and IPv6. Every school should be training students in IPv6 deployment now.

I am developing my IPv6 class materials and they are free for everyone to use. For the latest materials, go to and click on "CNIT 60". Every networking instructor, and every networking student, should get the Hurricane Electric IPv6 certificate. It's fun, not too hard to do, and it gives you a firm foundation for the transition that is coming very soon. Step-by-step instructions to earn the certificate are on my CNIT 60 page.

For more information, see this link:

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