On Tue, Mar 01, 2005 at 09:09:18PM +0100, Iljitsch van Beijnum wrote:
Unfortunately this mainly leads to bad connectivity as half of the IPv6 world filters /48.
As long as your two transit ISPs accept the /48 from eachother, you'll have redundancy so this is not fatal.
I consider 15-hop AS_PATHs crossing ponds multiple times and tunnels all over etc with 500ms+ RTT quite fatal, compared to let's say 3-hop AS_PATH all native.
And if we can write up a nice document that outlines how people can filter out "remote" /48s because having those in their routing tables has no added value, while allowing "close by" /48s that help optimize traffic flow, this could work out very well.
No, won't. The problem operators on the net don't update filters, let alone read "nice documents" how to do things properly. And there is still:
But if it gets out of hand, people can filter without breaking connectivity.
Wrong. You cannot filter PA-more-specific-multihomer-prefixes away without risking to lose connectivity to them. If the provider aggregate has routing problems (be it interdomain or even intradomain) and your transit cloud doesn't see the more-specific prefix announced by the multihomer, you lose connectivity. Especially in the case of the aggregate falling off the sky. A site behind upstreams who filter doesn't see the aggregate anymore, and because of filtering don't see the more-specific anymore too. POOF. There goes your connectivity. You still rely on the PA provider. You don't want that. PA-more-specific-multihoming fails (as a viable solution) as soon as people (especially transits) start filtering more-specifics. And looking at the IPv6 world today, this is already the case. Regards, Daniel -- CLUE-RIPE -- Jabber: dr@cluenet.de -- dr@IRCnet -- PGP: 0xA85C8AA0