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ipv6 addressing

IPv6 addresses are the new addressing mechanism for networking systems together

IPv4

The current model for setting addresses on the Internet is IPv4. A 32 bit IPv4 address might look like 192.168.16.45 - 4 blocks of numbers from 0-255. Each system in a network must have a unique address. Therefore IPv4 has a finite number of addresses available

255 x 255 x 255 x 255 = 4,228,250,625

thereby limiting the number of systems which can connect to the Internet. Although this number seems seriously large, when IP addresses are issued, they are often issued in large blocks with the result that large chunks are not actually used for example:

  1. a organisation might have 12 systems to connect to the Internet but they are assigned a block of 255 addressed from 194.132.45.0 to 194.132.45.255
  2. some technologies like HTTPS are designed to work with unique IP addresses so if a web hosts wants more than one HTTPS domain on a server, they need multiple IP addresses for a single machine.

As a result, IPv4 addresses are expected to run out sometime in 2012. After that date there are no addresses available so no new systems can be added to the network. Wikipedia has good articles on IPv4 addressing and address space exhaustion in particular

IPV6

One of the solutions envisaged was proposed as IPv6 where 128 bit addresses are constructed in 8 hexadecimal parts like

2001:0DB8:AC10:FE01:0000:0000:0000:0000

This structure has become the next standard offering a huge number of addresses available to each and every individual on the planet. At this time this seems rather excessive but it is envisaged that devices like domestic fridges and television sets will be connected to the network and require their own individual addresses so, for example, you can control you home TV from work or turn the oven on or ask the fridge if there is any beer. Again Wikipedia has a good article on IPV6.

Even at this stage, IPV6 is not used very much but obviously it is necessary to prepare for the changeover which is fast approaching. Already most operating systems, Unix & Windows, actively support IPv6 and many applications as well. A few ISPs offer fully functioning IPv6 connectivity but most people wanting to experiment with IPv6 must work through IPv4-IPv6 tunnels. Such tunnels are available from tunnel brokers (see wikipedia tunnel brokers). We currently use tunnels provided by Sixxs to interconnect our various networks.

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