Inside IPv6

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Think about how many devices we use in our personal and business lives that are connected to a network. When the Internet was first created, it was not intended for use by the general population. No one, including Al Gore, anticipated the Internet would find today's widespread use.

We are now running out of available IP addresses under the current addressing scheme called IPv4, which is limited to a maximum of 4,294,967,296 (232) addresses. This may seem like a lot of addresses, but consider that, according to the Internet Corporation for Assigned Names and Numbers (ICANN), the available IPv4 addresses will run out by 2011.

IPv6 Advantages
  • Easy configuration — Local devices will recognize each other and auto configure as necessary.
  • Ability to create ad-hoc networks quickly — good for rapidly connecting local devices and creating a temporary network
  • Supporting 3G and newer wireless telephone networks — Each telephone can have one or more dedicated IP address.
  • Will support larger packets up to 32Gb each — Yes this is correct you are currently limited to 64kb with IPv6.
  • Better security
  • Better quality of service

IPv4 vs. IPv6

There are many significant differences between the two addressing schemes, but the most obvious is that IPv6 was designed to handle about 3,403 × 1038 different addresses. That is approximately 1 trillion more than IPv4.

In terms of architecture, the two schemes are very different. IPv4 is categorized as classful, which essentially means that users requiring a static address were typically assigned a class B (65,534) or C (254) address. This is extremely inefficient, primarily because most assigned IP addresses were not needed. For example, if a company needs 300 IP addresses, it would waste 65,234 potential addresses. Now enter IPv6, which uses a scheme called Classless Inter-Domain Routing (CIDR), which permits the allocation of IP addresses to users based on the amount of addresses required. CIDR permits aggregation of contiguous addresses in a single supernet, which decreases the amount of data needed for routing tables or the complex sub-netting currently needed for some IPv4 configurations.

The key to CIDR is that all the routing information is included within the address using groups of CIDR blocks. It is prefix-based, which means that information about each packet, such as the address length, is specified in the header. For example, IPv4 information is included in the initial block, which ensures compatibility with IPv4 as well as IPv6 addressing.

The addressing will also look quite different. As a simple example, the well known private IP address (under IPv4) of, will be fe80:: Several conversion calculators can be found on the Web.

IPv6 addresses are written in eight groups of four hexdecimal digits. One feature of this addressing scheme is that leading zeros can be omitted for each group, and if one group contains four zeros it can be replaced by double colons (::).

IPv4 reserves a block of IP addresses for local use. These addresses start with IPv6 also provides private addresses, known as Unique Local Addresses (ULA), all of which begin with the prefix fc00::/7. In addition, IPv6 utilizes a pseudorandom algorithm that provides another layer of protection against the possibility that other network devices will end up with the same address and cause network collisions.

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