Routing of 2002::/16

[Pekka Savola]

On Mon, 10 Dec 2001, Dave Wilson wrote:
> >   On its native IPv6 interface, the relay router MUST advertise a route
> >   to 2002::/16.  It MUST NOT advertise a longer 2002:: routing prefix
> >   on that interface.  Routing policy within the native IPv6 routing
> >   domain determines the scope of that advertisement, thereby limiting
> >   the visibility of the relay router in that domain.
> >
> 
> Now I take it that this means that I must advertise 2002::/16 within my 
> own network, and to as many of my peers as I (and they) choose, but 
> there is no requirement to advertise it to the entire IPv6 internet. Is 
> this correct? If so, is it good practise to attempt to advertise 
> 2002::/16 widely, or selectively?

Yes.

Depending on your network connectivity, whether you want to provide free 
service etc. you may or may not advertise it to the whole Internet.  It's 
up to you.  The shortest paths win, so you probably wouldn't be getting 
all the traffic anyway.

Here, we're announcing the route with no-export community to all of our
neighbours even though there is no reason to be shy about it (we're
already advertising 192.88.99.0/24 to the whole Internet).

> I see also that it's forbidden to advertise prefixes longer than 
> 2002::/16, for good reason. This would seem to mean that packets going 
> from native IPv6 site --> 6to4 site are reliant on either the native 
> site (or their upstream) having a relay router, or on some kind person 
> advertising 2002::/16 to the entire internet. Is this so?

Yes, multiple sources advertise 2002::/16 to the whole Internet.  A route 
is required, in one way or the other.

This is IMO a major problem with 6to4 -- the path for return packets may
be very non-optimal.  This can only be remedied by more 6to4 relays.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords