Only 1 question: What about the companies that have a /24 out of the /20 0r /21 that are multi-homed? If the route rules are not carefully prepared the multi-homed customer then might be single-homed and tied to the upstream they got the IP's from. Thoughts? Jim
-----Original Message----- From: bdragon@gweep.net [mailto:bdragon@gweep.net] Sent: Thursday, April 17, 2003 3:56 PM To: nanog@merit.edu Subject: selective auto-aggregation
I believe we're losing the aggregation war. More and more entities are deaggregating, and not announcing their largest aggregates which makes prefix-length filtering less effective.
I'ld like to propose the concept of selective aggregation, whereby a router can be configured to aggregate based upon rules.
For example, if an RIR allocation boundary for a particular /8 is /21, that routes which are longer than /21 could be aggregated to /21 rather than discarded. Obviously, this would only be effective facing one's transit, since aggregating a peer would violate most peering agreements. In transit-free networks, this functionality would not be useful.
Similarly, the ability to auto-aggregate contiguous networks originated by the same AS, which could be applied even to routes with lengths shorter than an RIR boundary. This functionality could be useful facing ones peers.
This type of thing would need to be selective, since permitted deaggregation (no-export tagged routes with meaningful MEDs) can still be useful between entities which agree to such things.
If we can, I'ld like to avoid a holy war on whether deaggregating is someone's god given right, and stick to the premise that there are networks who will enforce aggregation policies, and want to do so in the most effective manner possible.