In 1981, the pioneers of the Internet developed a protocol known as IPv4. Over the past three decades, it has been the most widely deployed Internet Layer protocol in the world. Unfortunately, IPv4 uses 32-bit, four-byte addresses, meaning the amount of space available on the Internet is somewhat limited. Due to the unimaginable growth of the Web, the vast majority of the more than 4.2 billion available Internet addresses are currently being used. In fact, we are expected to run out of IPv4 addresses in early 2011.