Comparing ISATAP with other IPv6 transition technologies

A few weeks ago our own Lavanya Rathnam here on TechGenix published an excellent article explaining how ISATAP can be used to help transition your organization’s IPv4 network infrastructure to IPv6. But ISATAP isn’t the only technology you can use to help transition your IPv4 network to IPv6. It is, however, one of the better approaches short of ripping everything out and starting again from scratch. So I thought I’d take a moment and dig a bit deeper into configuring ISATAP in Windows Server environments and describe how ISATAP compares with other IPv6 transition technologies included in the Windows Server platform.

To do this I’ve adapted a few short excerpts from my book Training Guide: Installing and Configuring Windows Server 2012 R2 from Microsoft Press. While primarily geared toward individuals pursuing Microsoft Certified Solutions Associate (MCSA) certification, the book is also designed to help enterprise administrators develop real-world, job-role-specific skills by focusing on deploying and managing core infrastructure services in Windows Server. You can also use the book to build hands-on expertise through a series of lessons, exercises, and suggested practices as well as to help maximize your performance on the job. So if you have Windows Server deployed and want to learn more about how to administer the platform or fill in some gaps in your skills and expertise, you should buy my book!

Comparing IPv6 transition technologies

IPv6 transition
Let’s begin by exploring the range of different technologies you can use on the Windows platform to smooth your organization’s transition from IPv4 to IPv6. The ultimate goal, of course, of IPv6 is for IPv4 to eventually be retired and all nodes on all TCP/IP networks to use only IPv6. However, such a goal might take years, or even decades, to achieve. In the meantime, IPv4 and IPv6 nodes must be able to interoperate on the same network so that communications will not be disrupted, and IPv6 transition technologies make this possible. Windows platforms can be used to implement the following IPv6 transition technologies:

  • ISATAP — This transition technology allows IPv6/IPv4 nodes on an IPv4-only intranet to use IPv6 to communicate with each other and across the IPv6 Internet.
  • 6to4 — This transition technology provides automatic tunneling that allows IPv6/IPv4 hosts to establish IPv6 connectivity with each other across the IPv4 Internet. However, implementing 6to4 requires that the edge device (router) use a public IPv4 address.
  • Teredo — This transition technology provides automatic tunneling that allows IPv6/IPv4 hosts to establish IPv6 connectivity with each other across the IPv4 Internet even when IPv4 network address translation (NAT) devices need to be traversed. Because of this capability, Teredo is more suitable than 6to4 for small office/home office (SOHO) environments that use NATs to hide their private IPv4 addresses from the Internet.

In addition, Windows platforms support the following IPv6-to-IPv4 traffic translation technologies:

  • NAT64 — This technology is used to allow IPv6-only nodes to access IPv4-only hosts. The DirectAccess feature of Windows Server 2012 uses NAT64 to enable DirectAccess clients (which act as IPv6-only nodes) to access hosts on an IPv4 corporate network.
  • DNS64 — This technology is used to map IPv6-only address record (AAAA) name queries to IPv4 address record (A) name queries. Using DNS64 together with NAT64 enables IPv6 nodes to initiate communication with IPv4-only nodes with no changes to either node.
  • PortProxy — This technology allows IPv4/IPv6 TCP traffic to be proxied to IPv4/IPv6 TCP traffic at a different address. The technology is useful when nodes cannot communicate using either IPv4 or

Understanding ISATAP addresses

Let’s now key in on one of these transition technologies (ISATAP) in more detail. ISATAP enables unicast communication between IPv6/IPv4 hosts across the IPv4-only Internet. ISATAP works by encapsulating IPv6 packets with an IPv4 header so that the IPv6 packet can be sent over an IPv4-only network. This approach is called IPv6-over-IPv4 tunneling, and ISATAP uses automatic tunneling that does not require any manual configuration.

ISATAP addresses are assigned by ISATAP hosts to their ISATAP tunnel interfaces. An ISATAP address consists of a valid 64-bit unicast address prefix and a 64-bit interface identifier. The interface identify can be either ::0:5efe:w.x.y.z or ::200:5efe:w.x.y.z, where w.x.y.z is either a private or public IPv4 address, respectively.

On Windows platforms, IPv6 automatically creates a separate ISATAP tunneling interface for each LAN interface that has a unique DNS suffix. A link-local ISATAP address is then automatically configured on these ISATAP interfaces to enable IPv6 communication over an IPv4-only network without the need of assigning global or unique local ISATAP addresses to the interfaces.

In Windows Server 2012, you can use the Get-NetIPInterface cmdlet to list the interfaces on the computer (the command output has been truncated for display reasons):

PS C:\> Get-NetIPInterface -AddressFamily IPv6

ifIndex InterfaceAlias NlMtu(Bytes) InterfaceMetric ConnectionState
——- ————– ———— ————— —————
12 Ethernet 1500 5 Connected
14 Teredo Tunneling Pseudo-Inte… 1280 50 Disconnected
13 isatap.{DD59BFFD-706A-4685-9… 1280 50 Disconnected
1 Loopback Pseudo-Interface 1 4294967295 50 Connected

From the preceding output, you can see that the index number of the ISATAP interface is 13, which allows you to display more detailed information about the interface as follows:

PS C:\> Get-NetIPInterface -AddressFamily IPv6 -ifIndex 13 | fl

InterfaceIndex : 13
InterfaceAlias : isatap.{DD59BFFD-706A-4685-9073-647788046335}
AddressFamily : IPv6
Forwarding : Disabled
Advertising : Disabled
NlMtu(Bytes) : 1280
AutomaticMetric : Enabled
InterfaceMetric : 50
NeighborDiscoverySupported : Yes
NeighborUnreachabilityDetection : Disabled
BaseReachableTime(ms) : 30000
ReachableTime(ms) : 23000
RetransmitTime(ms) : 1000
DadTransmits : 0
RouterDiscovery : Enabled
ManagedAddressConfiguration : Disabled
OtherStatefulConfiguration : Disabled
WeakHostSend : Disabled
WeakHostReceive : Disabled
IgnoreDefaultRoutes : Disabled
AdvertisedRouterLifetime : 00:30:00
AdvertiseDefaultRoute : Disabled
CurrentHopLimit : 0
ForceArpNdWolPattern : Disabled
DirectedMacWolPattern : Disabled
EcnMarking : AppDecide
Dhcp : Disabled
ConnectionState : Disconnected
PolicyStore : ActiveStore

Understanding ISATAP components

As shown in the figure below, an ISATAP infrastructure includes the following components:

  • ISATAP subnets — An ISATAP subnet is a portion of an IPv4-only network on which ISATAP will be used for IPv6-over-IPv4 tunneling.
  • ISATAP hosts — An ISATAP host has an ISATAP tunneling interface, which it can use communicate with other ISATAP hosts on the same ISATAP subnet. Windows computers can function as ISATAP hosts using either link-local, unique-local, or global ISATAP addresses.
  • ISATAP routers — An ISATAP router is used to enable communication between ISATAP hosts on an ISATAP subnet and IPv6 hosts on an IPv6-capable network. Computers running Windows Server 2012 can function as ISATAP routers by configuring their LAN interfaces with appropriate IPv6 addresses, routes, and other settings.

IPv6 transition

Configuring ISATAP clients

You can configure a Windows computer to use an ISATAP router in the following ways:

IPv6 transition

Where you can learn more

The chapter these excerpts have been adapted from also covers IPv6 concepts and terminology in some detail and the underlying technologies for IPv6 transition on the Windows Server haven’t changed since Windows Server 2012 was released. So if you’re still pretty new to IPv6 you can come up to speed quickly on the basics by buying my book 🙂

And if you want some hands-on experience setting up ISATAP and other IPv6 transition technologies you can download the Test Lab Guide: Demonstrate IPv6 by Joe Davies from the Microsoft TechNet Gallery. You can use this guide use it to set up a test lab you can use to demonstration default IPv6 connectivity, 6to4-based IPv6 connectivity, and ISATAP-based IPv6 connectivity. Note however that this guide is kinda old as it requires that you use Windows 7 and Windows Server 2008 R2 for the systems you set up in your Contoso intranet.

Featured image: Shutterstock

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