Why to use IPv6 today
When I tell people that I’m using IPv6 in my home network, they ask me what it is good for. To be honest, at the moment it is more pain than good. Currently close to all servers are connected using IPv4. I do not expect this to change any time soon. Not even on the midterm. So why do I expect IPv6 to gain importance in the near future?
Mobile internet devices are getting mainstream. This creates a fast increasing demand for IP addresses. Current estimations expect that all usable IPv4 addresses are assigned to providers within one year. Several providers, such as German Telekom, started to work around the upcoming problem by assigning private IP addresses to the devices connected to their network. In order to allow you to use the net outside their own network, they use a technology called network address translation (NAT). With this technique, many computers share a single public IP address.
Using the internet through NAT is not a problem if all you want to do is browsing the web. Your device connects to the web site provider, the NAT system stores that it is you that wants these information and once the server answers, the NAT system forwards the data to your device. This is the first problem with NAT: Instead of blindly forwarding data, the NAT system has to analyze parts of the communication and store them. Of course, normal routers could do the same but NAT routers have to store the data, whether they are evil or not.
Aside the privacy issue, NAT is not a big problem for you, is it? It is.
All the world outside sees about you is your public IP address. If you are behind a NAT router this IP address is the same for several hundreds or thousands users. What if one of them behaves badly? Let’s say, someone keeps writing rubbish in Wikipedia articles. All wikipedia could do to stop this is to block the IP address this rowdy uses. But they no longer block the IP address of one rowdy. They block the IP address of one rowdy and some thousand friendly citizen.
Maybe you want to use more than one computer in your home. A computer, an iPhone, and an iPad. Since your provider will most likely not allow you to use more than one of its precious IPv4 IPs, you have to set up a NAT router on your own. While this is technically not too hard, there is a very limited set of private IP ranges. If the private IP range you want to use in your local network overlaps with the private IP range your provider uses, you will get problems.
Finally you might want to set up some kind of server at your home. Something like screen sharing or you want to use your printer at home while on the road. You might want to set up a virtual private network. (Read about FireSheep and you will want to use a VPN for your mobile device.) Without your own public IP, you can’t do that. IPv6 gives you more public IPs than you will ever need.
IPv4 will continue to exist for a very long time. I expect a change from IPv6 islands within a IPv4 internet to IPv4 islands within a IPv6 internet to happen within 10 years. I expect most internet servers (such as web servers, mail servers, etc.) to provide their services on dual stacks (IPv4 + IPv6) within 5 years. There will be a huge wave of newly used IPv6 addresses very soon. Riding a wave is the most fun when you’re in front of it.