Best practices for routing 6to4 addresses

Tim Chown tjc at
Wed Oct 18 14:32:25 CEST 2006

On Tue, Oct 17, 2006 at 05:00:58PM +0200, Daniel G. Kluge wrote:
> Hello there,
> I was wondering if there is some consensus on how to deal with 6to4  
> (2002::/16) addresses (and of course this applies to a certain extent  
> to Teredo).
> There are three ways how to configure this in an IPv6 network, and I  
> think I've seen all three:
> 1. Configure a 6to4 relay on each router (which has to be dual- 
> stacked) and use the local interface as a static route.
> 2. Have only one central 6to4 relay which is advertised internally  
> (and maybe further).
> 3. Pray that you learn 2002::/16 over one of your peers or transit  
> providers (and fail - hello AS16215)
> What's the way to go? (Apart from not using 6to4 or any other  
> automated transition mechanism)


JANET uses a single relay on the core network which advertises the usual
IPv4 anycast address over IPv4 links and 2002::/16 to connected IPv6 networks.
The service is not advertised outside of JANET.

This seems work well, though we see little 6to4 traffic.  SWITCH chose to
advertise their relay more publicly, and thus become something of a 6to4
traffic magnet in Europe and beyond (which has its good and bad points :)

In terms of stats, our logs for show 28850 hits over
IPv6 since the log was rolled overnight and in the same time 13 from 6to4 


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