The networks using these officially unallocated addresses are intended to be private, not visible to the global Internet. Nonetheless, their use can be detected when the private parts of networks connect to their public Internet facing connections, such as the connections to their service providers. The addresses leak in e-mail message headers, DNS queries and other random traffic. In some cases, this unofficial use can cause operational problems.

IANA staff has tried to research which /8s are being used in this way. In 2008 we sponsored research by Duane Wessels into which /8s see the most use. He reported on his research at OARC’s DNS Ops meeting and I wrote about it on this blog. Based on this work, we think the /8s with the most unofficial use are:

1, 2, 5, 14, 23, 39, 42, 100, 101, 107, 175 and 176

Duane Wessels’ research was part of a number of presentations that were part of an awareness campaign we worked on. This included talks at network operator groups and articles in industry journals and in some cases discussions with the users of the unallocated space where we could identify them. While we have discussed the issue with some of these network operators, we haven’t been able to speak directly to everyone making unofficial use of this address space because they tend to do so in private networks.

We know that newly allocated IPv4 /8s can be difficult for assigned users to use at first because old filters which block unallocated addresses are slow to be updated with new allocation information. There might be some extra operational difficulties with these particular /8s if unofficial users of the addresses try to communicate with the newly assigned official users of the same addresses.

The longer-term solution to this problem is for network operators to switch to IPv6 and to stop using the unallocated blocks entirely.

Over the next two years we will continue to allocate from these /8s when making allocations to the RIRs. The RIRs use about one /8 per month and so over the next couple of years we know that all of these /8s will be allocated.

One of the more interesting insights involved looking at network diversity. We want top-level domains to keep functioning no matter what is happening — any conceivable disaster shouldn’t knock a top-level domain off-line. One thing we ask is that top-level domains’ name servers be hosted in at least two distinct networks, so it is guarded against a failure (be it a technical failure, or some other business failure event).

Here is a map of all the country-code top-level domains, and one possibly measure of diversity — the number of “autonomous systems” their name servers are hosted in. Countries marked red are reliant on a single network, and if that network failed it could be disastrous for its users without alternatives. Those orange through green have increasing amounts of diversity in the networks that host their name servers:

If we take a minimum of two networks as our baseline requirement, we can look at how TLDs have met this criteria over a period of time — say the last five years:

The blue line shows IPv4 connectivity and it is pretty good, and rather consistent. But if we judge IPv6 connectivity against the same diversity requirement, shown as the green line, not even 50% of ccTLDs have this level of diversity. If we look at TLDs with any IPv6 it is a little better, but there is still about a third of all ccTLDs with no IPv6 connectivity at all!

The good news is the IPv6 trend lines are heading in the right direction, with the growth of IPv6 deployment even accelerating a little recently. Lets hope this continues so that these critical resources are stable not just for existing Internet users, but for future Internet users as well.

L.root-servers.net, operated by ICANN, became the seventh of the root servers to have it’s IPv6 address records (AAAA) added into the DNS root-zone. The addition of IPv6 service is part of ICANN’s ongoing commitment to act as a leader in enabling IPv6 services throughout the DNS.

The new IPv6 address is 2001:500:3::42

To access this service DNS operators should update their hints files. In fact checking that you have the latest hints file on a regular basis is always good operational practice.

The latest hints files are available at the following URLs:

ftp://rs.internic.net/domain/named.root
ftp://ftp.internic.net/domain/named.root

The root servers currently answering on IPv6 are:

A.ROOT-SERVERS.NET 2001:503:ba3e::2:30
F.ROOT-SERVERS.NET 2001:500:2f::f
H.ROOT-SERVERS.NET 2001:500:1::803f:235
J.ROOT-SERVERS.NET 2001:503:c27::2:30
K.ROOT-SERVERS.NET 2001:7fd::1
L.ROOT-SERVERS.NET 2001:500:3::42
M.ROOT-SERVERS.NET 2001:dc3::35

Unfortunately, even when production quality IPv6 transport and network infrastructure are available it is not always possible to deploy a completely IPv6 accessible network. One problem is the difficulties domain name registrants have when they ask their domain name registrar to include their IPv6 glue in the DNS. Not many domain name registrars support glue registration for IPv6 addresses. This limits their ability to provide an IPv6 DNS service.

The problem was discussed during Registries and Registrars’ IPv6 workshop on the last day of the ICANN meeting in Paris. Raúl Echeberría explained the problems that LACNIC has experienced in registering the glue they need for ns.lacnic.net.

Mohsen Souissi of AFNIC then explained that IPv6 support in domain name registries is no longer the hard work it once was. Most of the tools that are needed already support IPv6 very well and have done so for some time. He was followed by Jean-Claude Michot of BookMyName who explained that introducing support for IPv6 glue was not a complicated process and was done very quickly.

It is possible for a registrar to provide support for IPv6 glue registration without running IPv6 on their network at all and deploying an IPv6 network is now far less painful than it once was. Michele Neylon from Blacknight described a generally positive experience.

We hope that more domain registrars will start offering IPv6 glue registration, which will make it easier for domain name registrants to go ahead and deploy their own IPv6 networks.