Nov 15, 2011

IP addresses are being replaced with IPv6 in a California pilot program; why is there a need for a new Internet Protocol?

Comcast is starting a test deployment of IPv6 (Internet Protocol version 6) in California. What exactly is the difference between IPv6 and existing IPv4 anyway, and why is the change coming? What's wrong with existing IP addresses?

Hi wstark,

Here's a good background article that explains why the change is needed.


"Internet Protocol version 6 (IPv6) is a version of the Internet Protocol (IP). It is designed to succeed the Internet Protocol version 4 (IPv4). The Internet operates by transferring data between hosts in small packets that are independently routed across networks as specified by an international communications protocol known as the Internet Protocol.

Each host or computer on the Internet requires an IP address in order to communicate. The growth of the Internet has created a need for more addresses than are possible with IPv4. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with this long-anticipated IPv4 address exhaustion, and is described in Internet standard document RFC 2460, published in December 1998.[1] Like IPv4, IPv6 is an internet-layer protocol for packet-switched internetworking and provides end-to-end datagram transmission across multiple IP networks. While IPv4 allows 32 bits for an Internet Protocol address, and can therefore support 232 (4,294,967,296) addresses, IPv6 uses 128-bit addresses, so the new address space supports 2128 (approximately 340 undecillion or 3.4×1038) addresses. This expansion allows for many more devices and users on the internet as well as extra flexibility in allocating addresses and efficiency for routing traffic. It also eliminates the primary need for network address translation (NAT), which gained widespread deployment as an effort to alleviate IPv4 address exhaustion.

IPv6 also implements additional features not present in IPv4. It simplifies aspects of address assignment (stateless address autoconfiguration), network renumbering and router announcements when changing Internet connectivity providers. The IPv6 subnet size has been standardized by fixing the size of the host identifier portion of an address to 64 bits to facilitate an automatic mechanism for forming the host identifier from link-layer media addressing information (MAC address). Network security is also integrated into the design of the IPv6 architecture, and the IPv6 specification mandates support for IPsec as a fundamental interoperability requirement."

One thing is that IPv6 keeps us from running out of IP addresses. Currently IP addresses are 32bits, IPv6 uses 128 bit addresses, so there are lots more possible addresses. Now I'll admit that I didn't do the math on this (thank you Wikipedia) but the number of possible addresses using the current IPv4 is "only" 4.3 billion, where as with IPv6 it is 340 undecillion. And no, I didn't know that undecillion was a number either. There are some other differences related to how IPv6 functions, and there isn't universal support in operating systems. For example, webOS and Windows Phone 7.0 do not support IPv6 at all, whereas Ubuntu does. There is an article about the Comcast IPv6 rollout in California that you were asking about. http://arstechnica.com/business/news/2011/11/comcast-begins-limited-ipv6...

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