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Re: [RRG] Geographic aggregation-based routing is at odds with reality



On 18 jul 2008, at 9:47, Tony Li wrote:

The issue with this approach is again one of cooperation: those folks
performing the maintenance of the aggregation are NOT those that benefit from it. The up side is that if everyone were cooperative (you scratch my back, I'll scratch yours), then mutual aggregation would distribute both the costs AND the benefits. If providers could be enticed to enter into such a multilateral (and informal!) agreement, we could make significant progress.

I don't see that.

If I want to shrink my routing tables I can filter out any Canadian more specifics all over the world except in Canada, and instead put in an aggregate that covers the address space used in Canada.

(This requires that Canadian address space can be identified through a small number of prefixes and that I can easily make exceptions for more specifics to Canadian destinations that I can't reach through peerig inside Canada, but only elsewhere.)

If you are also a large network with customers in Canada, I don't care whether you also implement this aggregation or not. I can either do hot potato and give you the Canadian traffic close to the source and thus optimize for traffic flow, or filter those more specific, transport the traffic to Canada and then give it to you, optimizing for routing table size.

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