Hi, On Mon, Dec 08, 2003 at 10:01:53PM +0100, Jeroen Massar wrote: > There are currently quite some ISP's who filter anything >/35. > Generally ISP's should be filtering on allocation boundaries. > Thus if a certain prefix is allocated as a /32, they should not > be accepting anything smaller (/33, /34 etc) There is no commonly agreed-upon best practice for this yet. We do *not* suppress more-specifics from those address blocks, as we think it's a legitimate wish for certain networks to be multihomed, and currently there is no other solution than to go for the pragmatic approach, and just announce a /40 or even /48. I agree that things that are more specific than a /48 should not be out there. [..] > the ipv6 global routing table is quite small, but it could grow > quite large and when ISP's still don't filter correctly, or better > if ISP's don't aggregate it will explode and we will be needing > the follow up to BGP soon, which is more work for the IETF :) If every holder of an AS will announce one prefix at maximum (which should be doable by proper aggregation), the v6 BGP table would grow to about 20.000 entries. This is still manageable, although it would kill my good old Cisco 2500 that still has a full v6 BGP table... > As for which smoked filled room, this should be a task of the > RIRs, thus RIPE's IPv6 WG etc. but it usually takes place when > communicating between ISP's. Notice that many ISP's use Gerts list: > http://www.space.net/~gert/RIPE/ipv6-filters.html > > I would applaud a generic /32 that is 'allowed' to being cut up > into multiple /48's for the purpose of critical infrastructure. > But please, keep it to 1 *documented* /32. That way people will > know that they will see more specifics from that prefix and that > they should be accepting it too. As you cite my page, you will also know that it does not make a specific recommendation on the subject of "filtering things between /35 and /48"... Gert Doering -- NetMaster -- Total number of prefixes smaller than registry allocations: 57386 (57785) SpaceNet AG Mail: netmaster@xxxxxxxxx Joseph-Dollinger-Bogen 14 Tel : +49-89-32356-0 80807 Muenchen Fax : +49-89-32356-299