IP Address Exhaustion is a phrase used to describe the problem of the ever dwindling supply of IPv4 addresses. The Internet Assigned Numbers Authority (IANA), the folks that manage all IP addresses on the planet, has been telling us for quite some time that we are running out of addresses. We've known that the IP Addressspace is limited and small, relative to the number of computers and Internet-capable devices out there, but so far, there have been workarounds to keep things running.
Usage as of 2009
If you take a look at the Internet World Stats page you will see that as of 2009, there were an estimated 6.7 billion people on the planet. Of those, there are an estimated 361 million people with Internet access--that's about 5.3% of the world's population. That means that as more people "get online", we're going to need more addresses. We need a lot of equipment to build the Internet:
- Wireless Access Points to let you access the local network
- Switches to move your traffic to routers
- Routers to move your traffic on and off your network and out to the Internet
- Firewalls to let you safely into and out of the Internet
- Servers to house and deliver websites, video, music and let you poke, friend and tweet
- Load Balancers to make large sites like Google possible
- Caching servers, to speed up your Google, Facebook, YouTube and Hulu experience
- Satellite Gear
- Ground station receiveers and transmitters
- Satellites
- Microwave Towers
- Cellular towers and associated gear (gotta like and tweet from your phone, right?)
- Home computers
- Cell phones, tablets
- And lots of other equipment...
IPv4 only allows for 4.29 billion total addresses and between the people that need them, and the equipment that provides the service, we've just about used them up.
Complicating things is the fact that at the time IPv4 was conceived of, they never thought there would be this many computers on the Internet, so they just set aside whole blocks and marked them off as unusable on the Internet.
Unusable IP Address Space
- 10.0.0.0 – 10.255.255.255 (Private IP addresses, ~16.7 million IP addresses unusable)
- 127.0.0.0 – 127.255.255.255 (Loopback IP addresses, ~16.7 million IP addresses unusable)
- 172.16.0.0 – 172.31.255.255 (Private IP addresses, ~1.04 million IP addresses unusable)
- 192.168.0.0 – 192.168.255.255 (Private IP addresses, ~65.5 thousand IP addressesunusable)
- 224.0.0.0 through 239.255.255.255 (268.4 million IP addresses reserved for multicast use)
- and other reserved IP addresses
That’s a LOT of IP addresses unavailable for all our favorite Internet uses. But even all that space being set aside only brings us down to about 3.9 billion addressess. But, when you add in the calculations for Internet service providers who compete with one another and who have overlapping networks, you end up with most of the IP addreses being used by the Internet equipment itself, not the Internet. Worse, most of the Internet devices are in the United States, which is where most of the IP addresses are in use.