Testing your IPv6 via tunnelling

By on 21 Dec 2015

Category: Tech matters

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Tunnel brokers can provide you a way to test your IPv6 network Source: Photographing London, Flickr

During a recent APNIC Regional Meeting in Mongolia, I had an interesting discussion with one network operator about their organization’s plans for deploying IPv6.

They said they were making progress with deployment but a challenge they were coming up against was being able to test their IPv6 traffic externally.

This is a challenge that many networks currently face and can be attributed to lack of training and experience with IPv6, unwarranted cost of getting and testing transit and perceived risk of affecting the existing network. Some of these challenges can be overcome, as I informed my colleague, by using a tunnel broker service.

What is a tunnel broker and how can they help test IPv6 traffic?

Tunnel brokers provide network tunnels. These tunnels can provide a network service that the existing network does not support or provide directly; for example, using IPv4 infrastructure to route IPv6 packets between IPv6 networks. Think of IPv6 networks as islands and the only thing connecting the two is a tunnel or bridge.


There are a variety of tunnel brokers – some free, some subscription based – including IPv4 tunnel brokers, though most commonly the term is used to refer to an IPv6 tunnel broker.

IPv6 tunnel brokers have dual stack routers at either end of the IPv6 networks, which help route IPv6 packets via IPv4 networks.

APNIC offers eLearning courses that explain how to use dual stack and tunnelling techniques when transitioning from IPv4 to IPv6; and you can watch previous courses on APNIC Training’s YouTube Channel.

Four tips when using a tunnel broker

However, when you sign up with a tunnel broker you should be aware of the following:

  • You must have a router that is accessible via the Internet, i.e. it should have a public IPv4 address.
  • Take note of the IPv6 block that your broker gives you, as you will have to configure your machines to use that address to connect to the IPv4 address of the tunnel broker’s router.
  • Tunnels may have some limitations and latency issues, so should only be considered to test your network rather than to measure your traffic or actual production deployment.
  • Replace your tunnel broker with native dual-stack IPv6  as quickly as possible. Don’t see tunnel brokers as a permanent IPv6 solution, use them to learn and explore, but try and get to native IPv6 which follows your IPv4 relationships. This is better for everyone and avoids operational problems like pMTU discovery failure, fragmented IP, and assymetric delays comparing IPv4 and IPv6.
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