RE: survivability, rewriting

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

> I guess that if a host has the M6 mechanism working, it would be reasonable
> to assume that the site supports M6 and so that exit routers would rewrite
> the source address.

How so?
If we decide to standardize something which goes in the stack
then it will hopefully appear in future versions of various stack
implementations asynchonously and hosts with those new versions will appear in
an uncoordinated way in various parts of the network.
Thus you can't assume that somehow the site network admin is
in charge of what OS/stack version is installed on all the hosts
in their site.

> But anyway you could also use a bit in the router advertisement to
> communicate it to the hosts, right?

Yes, but you also need a way to get this information into all the routers
in the site. If the router renumbering RFC was widely implemented and used
it would provide a mechanism on which to add such additional information,
but that protocol doesn't seem to be implemented much.

My point is that if there are mechanisms which do not require such 
coordination between the site border routers and the hosts in the site
they are preferable (all other things being equal) since this coordination
is additional complexity i.e. additional places where things can go wrong.

> I don't see why the second part is conflicting with Iljistch goal...

It doesn't, which is why I called it "an observation" in the clarification.

  Erik