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Re: [RRG] Re: Fast and sparse mapping?



On 21 sep 2008, at 5:52, Brian E Carpenter wrote:

Well, if there is some number like 2^23 or 2^27 of prefixes active
in a 64-bit prefix space, and they don't aggregate, that seems sparse
in exactly the sense of a sparse matrix. I'm not suggesting this is
fundamentally different (except in scale) from today's BGP4 situation
of something like 2^18 prefixes active in a 32-bit space.

I'm not aware of any solutions other than TCAMs or Patricia tries
for fast lookups in such a space, whether it's for mapping or
for forwarding.

How helpful would it be if the prefixes were non-sparse? I.e., 2^25 prefixes out of a /26.

Currently the RIRs are being extra sparse on purpose (reserving a /44 for everyone who gets a /48) and I've long argued that this doesn't have the intended helpful effect in practice but it is harmful because of the increased sparseness.

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