Re: 6to4 considered a bad thing

[Brian E Carpenter <brian.e.carpenter@gmail.com>]

On 2008-02-02 15:44, Alain Durand wrote:
> 
> 
> On 2/1/08 7:17 PM, "james woodyatt" <jhw@apple.com> wrote:
> 
>>> Is ISP X suppose to announce a
>>> de-aggregate of 2002://16? That would create a huge increase in the
>>> routing
>>> table size...
>> That's clearly not a good idea.
> 
> Now, please help me reconcile how can a return relay for ISP X *only*
> advertize 2002::/16 (and nothing smaller) and not offer free return transit
> for people that are not its customers?

Indeed. RFC 3056 explicitly says that the scope of such an advertisement
has to be limited by policy.

   3. A relay router MUST advertise a route to 2002::/16 into the native
   IPv6 exterior routing domain.  It is a matter of routing policy how
   far this routing advertisement of 2002::/16 is propagated in the
   native IPv6 routing system.  Since there will in general be multiple
   relay routers advertising it, network operators will require to
   filter it in a managed way.  Incorrect policy in this area will lead
   to potential unreachability or to perverse traffic patterns.

      Brian