Configuring a shared/public IPv6 tunnel with Cisco IOS

[davidstrauss]

The configuration block provided in the Member Tools interface only sets up a local tunnel from the router to Sonic.net. Since Cisco IOS devices rarely run too many services themselves, the tunnel is usually the first step to useful IPv6 routing. (The Cisco example configuration has a typo in one of the tunnel names, too.)

With this configuration, network devices on your LAN will autoconfigure publicly routable IPv6 addresses that the router will process through the tunnel. Nothing like NAT will stand in the way, so consider the security implications.

I'll refer to the "Cisco" example configuration values and the values from the "View/Request Tunnel" screen. Values requiring substitution will be in <angle brackets>.

Open a Cisco IOS configuration terminal:

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config term

Enable IPv6 capability:

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ipv6 unicast-routing
ipv6 cef

Configure the 6in4/Tunnelbroker tunnel:

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interface Tunnel0
 description Sonic.net IPv6 Tunnel
 no ip address
 ipv6 address <"ipv6 address" from the Cisco example>
 ipv6 enable
 tunnel source <"tunnel source" from the Cisco example>
 tunnel mode ipv6ip
 tunnel destination <"tunnel destination" from the Cisco example>

Use it as the default IPv6 route:

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ipv6 route ::/0 <"Transport" from the View/Request Tunnel screen>

The route may work by just specifying the tunnel, but this is how I have it configured. Let me know, and I can update the directions.

Figure out a reasonable address given the "Network" Sonic gives you. The value is a "/60" pool, but we'll set up a reasonable "/64" pool. Here's how to do that.

Get the "network." It should look something like this (your XXXX will differ, and parts even before that might but don't between my two Sonic.net accounts):

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2001:05a8:0004:XXXX:0000:0000:0000:0000/60

Create a "/64" address and pool by taking the address up to the XXXX part and suffixing with ":1::1/64". You should get something like this:

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2001:5A8:0004:XXXX:1::1/64

Configure your LAN interface to use it :

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interface <Your LAN Interface>
 ipv6 address 2001:5A8:0004:XXXX:1::1/64
 ipv6 enable

Cisco IOS will automatically advertise the route to other machines, which should autoconfigure themselves to use addresses with the proper prefix to be routable.

Once it's tested, don't forget to "copy running-config startup-config" to preserve the configuration on restart.

If you get stuck at all or want to do some firewall setup, this page was very helpful:
http://wiki.nil.com/IPv6_over_IPv4_tunn ... nnelbroker