Internet surfing may get a little bumpy tomorrow as a number of major Internet entities start putting the IPv6 protocol to a serious test. At present, the majority of websites run on IPv4 -- a protocol that has served us well until this point. The trouble is that the available IPv4 addresses have all been allocated -- they have run out. When the World IPv6 Day test takes place, a number of companies including Facebook, Yahoo, Google, YouTube, Cisco, Akamai and Meebo will start putting their IPv6 networks through their paces. Their IPv4 networks will still be operational but the combination of IPv4 and IPv6 will cause some users issues. Google has predicted as many as 0.5 percent failed network requests. Facebook is more optimistic and predicts that just 0.03 percent of requests will fail. If you want to know whether your computer and/or browser are up to the task, simply connect to the IPv6 test page and see how things work out. Why do we need IPv6? This is a typical IPv4 address: 74.125.93.99. If you type it into your location bar it will take you to Google.com. The trouble is that you can only have four sets of digits and the digits must fall within a certain range. When all things are taken into account there are approximately 4.3 billion available addresses. IPv6 offers a lot more numbers. This is a typical IPv6 address: 2001:4860:0000:0000:0000:0000:0000:0000. If your browser is IPv6 compatible and your ISP supports IPv6, typing the eight sets of four characters will also take you to Google. However, it is much more likely that you will simply get an error message because either your browser or ISP will not be up to the challenge. Incidentally, Google owns some 7.9 x 10^28 (79 billion billion) IPv6 addresses, from the first in their series (shown above) all the way up to 2001:4860:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF. Now, if Google acquiring all of those IPv6 addresses makes you feel a little nervous, consider this -- the protocol allows for some 5 x 10^28 addresses for every person on the planet. There are plenty of addresses to go around. Back to the big test -- what could go wrong? If the predictions are correct, a few people might have trouble accessing sites. If things go really badly, a whole bunch of people might briefly lose access. On the flip-side, a lot of useful data will be gathered and the world will take a few tentative steps in the direction of a better Internet protocol. At any rate, World IPv6 Day is just a test, so any access issues should only be temporary.