>> Mainly, that it has a larger address space. With IPv4, addresses are getting scarce. >> With IPv6, there will not be an address shortage in the foreseeable future. The
…above answer is a simple one, but doesn't answer why more IP addresses are needed. Realistically there is already a shortage of IP addresses under IPv4. The only reason most people don't notice it is because their IPv4 traffic is routed through one router to another and yet another and so on. This complex configuration of routers segmenting and regulating different parts of the Internet guarantees that even though IPv4 has a limitation of 4 billion addresses it can connect more then 4 billion Internet devices (Computers, Cell Phones, Etc.). This has a cost though. This complex game of smoke and mirrors greatly inhibits your Internet connections true speed. So in other words your not getting anywhere near the speed you think you are even if you have a top-of-the-line FIOS connections. IPv6 would greatly reduce the complexity by awarding each device it's own IPv6 address. Greatly reducing the lag, delays, and bottlenecks caused by all these tricks. Furthermore alot of the new IPv4 technologies such as multicast and packet security are not naturally part of the original protocol. As such they require alot of software modification which in turn translates to more memory usage and more programs running. IPv6 internalizes, standardizes, and in effect reduces the overhead needed by these features. Thus increasing speed. Overall with all the overhead that IPv6 shaves off it could be expected to run at least 2.5 times that of an IPv4 connection rated at the same bandwidth (i.e. 1.5mbps). Standardized 4g mobile broadband is taking advantage of this big time and may even finally give DSL and Cable the real competition they both deserve. Look at http://www.clearwireless.com/. For $55 (plus the investment in the Mobile Stick or Wireless MiFi router) you can have unlimited usage of average speed of 6Mbps and throttling to 10Mbps. Add this to the fact that 4g has an ultimate limitation (in theory) of 10Gbps (10,000Mbps) and you'll see a reason to be excited. No more wires, no more paying line fees to the FCC. Get a small netbook with a Voip account and you can almost kiss that smartphone goodbye. (MORE) 
