So Philip Smith / Geoff Huston's CIDR report becomes worth a good hard look today

Chris Woodfield rekoil at
Thu Aug 14 00:20:16 UTC 2014

> Pruning FIB entries, on the other hand, can be done quite safely as
> long as you're willing to accept the conversion of "null route" to
> "don't care." Some experiments were done on this in the IETF a couple
> years back. Draft-zhang-fibaggregation maybe? Savings of 30% in
> typical backbone nodes looked possible. That's 30% of your TCAM
> reclaimable.

Hence the “when programming the TCAM” part of my original statement :)

> For the moment it seems to be cheaper to just build bigger TCAMs.
> Cheaper for the router vendors anyway.

I think of it more like “why spend development dollars on a feature that will cause my customers to keep their existing hardware longer and delay upgrades?” Yes, vendors do think like that.


> Regards,
> Bill Herrin
> -- 
> William Herrin ................ herrin at  bill at
> Owner, Dirtside Systems ......... Web: <>
> Can I solve your unusual networking challenges?

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