How ISATAP Works and How It Can Help You Migrate to IPv6 - Guest Blog [Archived]

By Jennifer Bly

Companies are developing different solutions for IPv6 deployment – here is a blog from a Microsoft Engineer that explains a bit about the approach they have chosen. How is your organization implementing IPv6?

Guest blog post by Gregg O’Brien

It’s no secret by now that IPv6 is the way of the future. Many IT/Network administrators know that they will inevitably be required to start moving towards IPv6 sooner or later, but the idea of migrating servers, applications, and network infrastructure is a large undertaking.

Fortunately, along with IPv6 came a series of transition technologies including ISATAP to make the switch to IPv6 easier.

ISATAP stands for Intra Site Automatic Tunneling Address Protocol and is defined in RFC 5214. ISATAP is an interface that hosts can use to pass IPv6 traffic over IPv4 networks. It does this by taking an IPv6 frame and applying headers to the frame with IPv4 network information. The hosts can then send this frame over the network to an IPv6 host, which can then process the IPv6 frame contained therein.

ISATAP is pretty easy to recognize. Its addresses are formatted in a very unique way. Here is an example of an ISATAP address:

2002:9D36:1:2:0:5EFE:192.168.12.9

If you look closely, you will notice that the first portion of the address, 2002:9D36:1:2:0:5EFE: is formatted like a typical IPv6 address. The subsequent portion of the address looks like an IPv4 address – 192.168.12.9. The format of this address provides some key information:

1. It is a valid IPv6 address that can be used for IPv6 communication

2. The presence of the IPv4 address indicates the IPv4 information that will be used to shuttle the IPv6 traffic over the IPv4 network.

But why would we want to transport IPv6 traffic over the IPv4 network? Why not just continue using IPv4 then?

Well, the idea here is to facilitate transition to IPv6. Consider the following scenario:

An existing IPv4 network in place with several hosts and applications.

Investing in overhauling the infrastructure to accommodate IPv6 is a longer term project, but the goal is to do as much with IPv6 now, to save work later.

ISATAP can help here allowing IPv6 networks and IPv4 networks to talk to each other. So as the network expands, new hosts and network gear can deployed with IPv6 instead of IPv4, but still communicate with the legacy IPv4 portions of the network.

Here we now have two segments of the network, one running IPv4, the other running IPv6. With the use of an ISATAP router and by enabling ISATAP on the hosts present in the IPv4 network, native IPv6 can be deployed on the new network segment. As time passes and hardware/applications are decommissioned, the IPv4 network can be phased out until the organization is fully operational on IPv6.

Hopefully that gives you some ideas about how to get an IPv6 project started in your own environment using IPv6!

Gregg O’Brien

Field Engineer

Microsoft

Blog: http://blogs.technet.com/b/mspfe/archive/tags/gregg+o_2700_brien/

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Any views, positions, statements or opinions of a guest blog post are those of the author alone and do not represent those of ARIN. ARIN does not guarantee the accuracy, completeness or validity of any claims or statements, nor shall ARIN be liable for any representations, omissions or errors contained in a guest blog post.