[6bone] separating IPv6 experimental from production traffic

[Jeff Barrow]

> This shouldn't be too hard, actually.  The main (only) complaint
> I've seen is bad routing over the experimental network, to be
> more precise, bad routing of _production_ packets over the 6bone.
>
> Here is my naive proposal:

Here's my even more naive proposal....

> 1) everybody can still have ipv6-over-ipv4 tunnels like today

> 2) peers notify each other whether their network is production
>    or experimental

> 3) experimental (3ffe::/16) pTLAs announce only 3ffe:: prefixes
>    to their production (2001::/16) peers
>
> 4) experimental pTLAs announce all prefixes to their 3ffe::/16
>    peers

Even better, change 3) and 4) to:

3) experimental pTLAs announce whatever they want to, but the production
peers all filter out incoming 2001::/16 prefixes from them.  This way,
even if an experimental pTLA messes up and starts announcing all prefixes
with their own ASN, or gets hit by that dreaded withdrawal bug, the
2001::/16 network will still be operational to itself--just the 3ffe://16
prefix may be bad.

Production pTLAs announce all prefixes to everyone, and listen from
other production pTLAs without the 2001::/16 filter.

This will, of course, require all production networks to be interconnected
by way of production networks only.  However, this method should be much
easier to accomplish, as only production pTLAs need to make configuration
changes to set this in place by adding a simple filter, instead of relying
on the experimental pTLAs to filter outgoing announcements (and trying to
contact them all); we just have to deal with the production-level pTLAs.

> 5) production networks announce all prefixes to everybody