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World IPv6 Day

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Back in November, it looked like there were less than 100 days of IPv4 left before all the assignments were allocated. Due to acceleration of IP address assignment, it is widely expected we will hit that mark before the end of January 2011.

Several IPv4 resource sites are predicting the end of IPv4 addresses either already or in the next week. The counter to the right is provided courtesy of Hurricane Electric.

At the moment, the IANA allocated IPv4 space has 7 top-level blocks (known as /8) left, each of which contain 16½ million IP addresses. At the time of writing, the following IPv4 blocks are unallocated:

  • 39/8 (i.e. 38.x.x.x)
  • 102/8 (i.e. 102.x.x.x)
  • 103/8 (i.e. 103.x.x.x)
  • 104/8 (i.e. 104.x.x.x)
  • 106/8 (i.e. 106.x.x.x)
  • 179/8 (i.e. 179.x.x.x)
  • 185/8 (i.e. 185.x.x.x)

Once these are allocated, IANA will have no further IPv4 addresses to give out.

It's worth explicitly observing that when these are allocated, IPv4 availability won't disappear immediately (for a start, it will have released another 117½ million addresses to be used). Each block is assigned to one of the Regional Internet Registries (RIRs) who then allocate space in the form of /24 addresses (e.g. 38.0.0.x) to ISPs or other customers who request them. So there will be a pool of available IPv4 addresses managed by the RIRs for the remainder of this year, and possibly part of the next as well.

RIPE-436 defines what happens in the exhaustion scenario; the final 5 unallocated blocks are served to individual RIRs. So if (say) APNIC or ARIN request another 2 blocks, the remaining five will be immediately handed out. It's expected that this scenario will kick in before the end of January 2011.

World IPv6 day

To try and encourage adoption of IPv6, the ISOC in conjunction with Google, Facebook and others have proposed a World IPv6 Day on 8th June 2011. Although Google supports IPv6 at the moment, it is only done if you explicitly go to (which resolves to 2a00:1450:8006::93 from the UK). If you have IPv6 connectivity, you can already consume a subset of services.

Google have previously not added IPv6 to their main sites since in a small number of cases, it can cause delays if DNS servers are incorrectly configured. However, signs are that is changing. In September 2010, one of Germany's largest technical sites, performed an experiment to enable IPv6 connectivity for all browsers. It was so successful that they left the IPv6 connectivity in place and it has been visible to both IPv4 and IPv6 networks ever since.

Part of the goal of the World IPv6 day is therefore to test whether the initial configuration problems are still relevant, as well as to highlight the lack of IPv4 addresses and encourage the use of IPv6.

To determine whether your connectivity is IPv6 enabled, you can visit which will report on your connectivity, and suggest areas for improvement if required. You can read previous IPv6 coverage on InfoQ.

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