Re: [Int-area] New Version Notification for draft-li-int-aggregation-00.txt

Dino Farinacci <farinacci@gmail.com> Fri, 25 February 2022 23:07 UTC

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From: Dino Farinacci <farinacci@gmail.com>
In-Reply-To: <YhiNEDhMoo2HRVPz@faui48e.informatik.uni-erlangen.de>
Date: Fri, 25 Feb 2022 15:07:05 -0800
Cc: Tony Li <tony.li@tony.li>, int-area@ietf.org
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To: Toerless Eckert <tte@cs.fau.de>
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Subject: Re: [Int-area] New Version Notification for draft-li-int-aggregation-00.txt
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> b) auto-aggregation within routers from routing-plane to forwarding
>   plane. Aka: Just don't populate the poor HW tables with all those
>   non-aggregated prefixes, but calculate the minimum number of
>   sufficient shorter prefixes.

We did that in year 2000. It is/was called FIB compression. It is useful in routers where a large number of routes shared the same next-hops. What I should really say, it benefits routers with less interfaces because the set is smaller. On the edge, like a PE router with DS3s to 100s of customers (circa year 2000) FIB compression didn't help that much when the customer would advertise non-compressible prefixes.

But it IS a useful feature at the expense of clever FIB engineers figuring out how to implement it on their respective company's hardware platform.

> E.g.: If we would have a better architecture, including LISP, we would
> arguably have a less than inexorable tie... i think.

You still have to aggregate locators.

Dino