[6bone] non-global address space for IXs (was: 2001:478:: as /48)

[Stephen Stuart]

> There is a reason why IX space should not be exported, namely to 
> prevent routing issues. Since eBGP learned routes are better than a 
> iBGP learned routes.

Some networks define BGP policy to correct that behavior with respect
to IX networks.

Some networks put IX connected routes into their IGP, overriding BGP
(I occasionally have to remind a network that "passive" is desirable
in that regard).

Regardless of the specific details, networks have the ability to put
mechanisms into place to prevent themselves from learning external
paths to what should be connected routes, rather than relying on other
networks not to announce them.

Stephen