RE: draft-ietf-multi6-multihoming-requirements-03

["Tony Hain" <alh-ietf@tndh.net>]

Iljitsch van Beijnum wrote:
>  ...
> >                 source
> >                   |
> > 		  .
> > 		  .
> > 		  |
> >                 upstream
> >                 /     \
> >        transit-l       transit-r
> >                 \     /
> >                  dest.
>
> Isn't this a bit oversimplified? This assumes there is a single place
> where all decisions can be taken. If this is true, then we haven't
> achieved full multihoming (there is still a single point of
> failure.) In
> reality, things will look more like:
>
>        Source
>        /    \
>       A      B
>      / \    / \
>     C   D--E   F
>      \ /    \ /
>       G      H
>        \    /
>      Destination
>
> Since selecting the link over AS H to the destination rather
> than the link
> over AS G means (potentially) influencing the routing
> decisions made in A,
> B, and E (and of course the source), this goes directly against the
> current distance path routing and hop-by-hop forwarding paradigms.

And perpetuating the idea that Dest has any influence on routing beyond
G & H where it is paying for service, amounts to a fraud on the scale of
the current accounting scandals. If Src prefers A who in turn chooses to
prefer C, there is nothing Dest can do to change that. Any requirement
that states one AS MUST be able to affect the policy of another AS will
simply be ignored, if not by the implementations, certainly by the
target AS where the policy is attempting to be overridden.

> However, IDPR should be able to handle this quite nicely.
>
>

To be seen.