Re: v6 deployment in general [Re: tunnel broker deployment [RE: Tunneling scenarios and mechanisms evaluation]]

[Erik Nordmark <Erik.Nordmark@sun.com>]

> > > The problem is worse with transition mechanisms, especially the ones 
> > > which traverse NATs, but the situation may improve as soon as we can 
> > > get rid of them.  In any case, such mechanisms can provide a stable 
> > > as long as they can keep the NAT/IP mappings stable -- which is, for a 
> > > properly designed application, maybe sufficient.
> > 
> > I guess I don't understand what "such mechanisms" refer to above.
> > I don't know if mechanisms like Teredo can provide a stable IPv6 address 
> > when the nat mappings change, but doing TB/UDP for nat traversal should be
> > able to provide stable IP addresses/prefixes in this case.
> 
> The point is to keep the NAT (etc.) mappings open as long as possible
> so that they don't change -- and if they change, that'd be due to ISP
> trying to enforce the user to a specific policy (e.g., changing v4
> addesses on the fly) -- and I'm not sure if it's worth trying to
> outsmart ISPs.  Stupidity always wins, with the customer in even a
> bigger mess in the end.. :-/

I still don't understand what you were trying to say in the first paragraph
above.
That paragraph doesn't take into account that one can build
tunnel broker UDP tunneling schemes where the IPv6 address/prefix
is stable when the NAT mapping changes.
Was that paragraph only talking about Teredo? I read it as attempting to
make a more general statement.

On the third paragraph above, the NAT mapping might change for
multiple reasons - one of them being the ISP forcing a new external IP
address of the NAT box. Others being the NAT state timing out for various
reasons (having lived 3 years behind a ISDN NAT box which looses the UDP
port mapping when the ISDN line is dropped due to lack of traffic
I've seen this).

   Erik

One can build