Best practice for running 6to4 relays (was Re: 6to4 borkeness)

[Kevin Day]

On Mar 19, 2008, at 4:43 PM, Michael Taht wrote:
> 1) I am curious as to what best practice would be to correctly setup a
> 6to4 router for a small ISP, announcing the route is valid just for  
> ips
> within my network - and not incurring the entire weight of australia
> trying to route through my gateway? (significant bandwidth charges  
> here)
>
> There seems to be lots of documentation on the web on how to use  
> 6to4 as
> a client, but zero on how to setup a router. (or why not to try) Is it
> even possible to do right? Conf files to setup on cisco gear or  
> quagga,
> explanations of how to avoid asymmetric routes, PMTU problems, etc
> highly desired.
>

On our end, this is what we've got:

Dedicated box doing nothing other than 6to4. It's a dual P3 866 Xeon,  
and it's pretty much got 99% idle time on it.

This box uses Quagga to announce 192.88.99.0/24 and 2002::/16 to our  
core router. This way if the box dies, our announcements get withdrawn.

Another box acts as a 6to4 client, and checks the operation of the  
relay every 60 seconds. It makes sure it's properly encapsulating/ 
decapsulating data, and at least 7 of 10 "important" v6 sites are  
reachable. If only 7 are, it pages our NOC mail alias. If 6 or less  
are reachable for more than a few minutes it kills the relay's BGP  
announcements until we look at what's wrong.

We're decently well connected (10 of the 43 paths on route-views for  
192.88.99.0/24 go to us), but total traffic is still really pretty  
small. The occasional burst over 100mbps often enough to justify a  
GigE port for this, but average use for our Chicago relay is less than  
10mbps. Average use for our Amsterdam relay is less than 30mbps.

You can do the same for a local network, just don't let those  
announcements leave your AS.

-- Kevin