IPv6 reaches another milestone

On February 4th the Internet Assigned Numbers Authority(IANA) added AAAA records for IPv6 addresses on four root servers, effectively adding the possibility for two hosts using IPv6 to communicate over the internet without relying on a IPv4 network by using the 6to4 system.

IPv4 address space is estimated to be fully used by as early as 2009 and though this date is still subject to debate, the need for IPv6 will come very soon. Countries like China, which are now experiencing massive increases in internet usage, will keep pushing the need for IPv4 addresses in the coming years, making the transition imperative.

IPv6, among other things, allows for 2^¹28 addresses. That's theoretically, because the IPv6 addressing architecture will leave some of them unassigned. Still, 2^128 addresses is a really big number of addresses, 256 tredabytes, or whatever equivalent IEC notation - nonexistant yet - if I did the math right. That's more than a trillion addresses per square centimeter of the surface on the planet, even toasters can have their own IP address now.
Currently, SI notations stop at the Yottabyte, or 2^80.

Not all is good though, since IPv6 was designed to allow every device to have it's IP address. This was cause for concern, since privacy issues would be a reality when using stateless auto-address configuration, which uses the unique 48bit MAC address of the network device. Fortunately a solution was devised, known as RFC3041.
Another problem is the lack of native NAT mechanisms, a simple solution to keep hackers away from your network. The possibility of ISPs charging the internet service fee by network device can be of concern, especially with the lack of NAT capabilities. NAT will eventually be implemented somehow in IPv6 networks, experts say, but that is not possible as of now.
The last problem is the bigger header, double of the minimum size from IPv4's header, causing a slightly higher response time from connections due to the increased overhead. It becomes worse because small packets have a minimum MTU of 1280bytes for IPv6 packet while the IPv4 allows for 576bytes.
The increase in bandwidth will eventually mitigate that problem, especially after today, when the 6to4 mechanism isn't needed to allow for IPv6 communications. Also, IPv6 allows for what is called Jumbograms, up to 4GiB from the base 64KiB packet size limit of IPv4, leaving the overhead concern for the MTU capabilities of the network devices.

In the end, some difficulties are likely, but there are good benefits coming with IPv6, let's hope that ISPs don't keep pushing IPv4 until some real problems with addressing space, or lack thereof, start to occur.