Multihoming - Resilience or Independence

> > That's why filtering /20 only without re-aligning the holes 
> in the block
> > won't
> > work. In the end /20 make the routing table looks pretty 
> but they are
> > black-holing
> > lots of traffic.
> 
> Well, it won't. The proposal for filtering is to filter on assigment
> boundary, and for swamp space filter on /24. Now, what will break is
> people punching holes in their PA space for multihomed users. Funny
> enough, this has never been discussed (to my knowledge) as a 
> problem in
> PTOMAIN WG of the IETF. There the argument was for traffic 
> engineering and
> commercial relationships...
> 

Even for PI and swamp space, if the organization divides their space among
different ISPs for
multi-homed links. You still got a problem.   

> > As we all agree that re-assign address is NOT practical at 
> all thus just
> > filtering
> > /20 block is not a good solution.
> 
> That is not the suggestion. See above. The assignments per 
> block and RIR
> is well known.

Well known and lots of holes in it. That's the problem.


Ping Lu
Cable & Wireless USA
Network Tools and Analysis Group
W: +1-703-292-2359
E: plu at cw.net