Windows configuration

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This article is for tips on configuring Microsoft Windows workstations to use IPv6.

Ways to access a command-line prompt

  • Windows-R, then "cmd" in the prompt, then click "OK."
  • Start -> All Programs -> Accessories -> Command Prompt

Disable the automatic Windows tunnels

Enter the following commands in a command-line...

    netsh interface ipv6 set privacy state=disable
    netsh interface ipv6 6to4 set state state=disabled
    netsh interface ipv6 isatap set state state=disabled
    netsh interface ipv6 set teredo disable

Add or delete a static IPv6 address

    netsh int ipv6 add add "name of adapter" IPv6 address
    netsh int ipv6 del add "name of adapter" IPv6 address
  • You can rename your network adapters in the Network Control Panel to make them easier to manage.

Check or Set MTU for IPv6 SixXS tunnel

If you get timeouts connecting to some IPv6 websites but not others (e.g., check your MTU. By default SixXS tunnels only support an MTU of 1280. This can be modified from your SixXS tunnel information page upto a maximum of 1480, but best to leave at 1280 unless you really know what you are doing.

One should never actually have to change the MTU, as IPv6 supports a mechanism called "Path MTU Discovery". When a host sends a packet that doesn't fit over the network link (eg your tunnel), the router that notices this responds with an ICMPv6 Packet Too Big. The sending host receives this ICMPv6 Packet Too Big and then can make it's packets smaller. The minimum IPv6 packet size is 1280. As such, any link should support packets sized 1280. The problem that might occur now is that somewhere on the link between your host and the host you are communicating with, something is filtering these ICMP messages or one of the ends of one of the intermediary links is misconfigured. In those cases the ICMPv6 Packet Too Big is not transmitted/received/processed correctly and large packets simply disappear into the void. This will then make your connection stall. A good way to find out if there might be PMTU issues is to use the 'tracepath6' tool, which unfortunately is only available on Linux though. Other trick is to use ping6 and specify that packets should not be fragmented. Then test if for large packets you get a return message for ICMPv6 Packet Too Big or not.

The following command will show you all of the IPv6 interfaces and MTU settings for those interfaces. {Tested on Vista SP1}

    netsh interface ipv6 show subinterface

The following command will set the specific adapter MTU to 1280.

    netsh interface ipv6 set subinterface "name of adapter" mtu=1280
  • By default the aiccu windows command line utility will rename the adapter from "Local Area Connection X" to "sixxs"

Restarting an IPv6 connection (non-Vista systems)

  1. Start -> Control Panel -> Network Connections
  2. Right-click the correct adapter entry, then left-click "Properties."
  3. Uncheck the IPv6 protocol entry, then click "OK."
  4. Right-click the same adapter entry, then left-click "Properties."
  5. Check the IPv6 entry, then click "OK."

Service redirection

TCP services can be redirected from IPv6 to IPv6 using the PortProxy feature.

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