any dangers of filtering every /24 on full internet table to preserve FIB space ?

William Herrin bill at
Mon Oct 10 18:37:20 UTC 2022

On Mon, Oct 10, 2022 at 11:18 AM Jeff Tantsura <jefftant.ietf at> wrote:
> There has been a number of efforts to implement FIB (actually BGP RIB) compression.
>  There’s a white paper from MS research; I recall Spotify talking of running off-box BGP
>  compression SW and re-injecting summarized BGP RIB;

Hi Jeff,

Actually, I was talking about FIB aggregation/compression where you
take a full BGP RIB but optimize the prefixes placed in the local FIB
so that you don't need a FIB entry for every RIB entry. Solid FIB
compression can give you a 50% savings in FIB entries without altering
the next hop selected for any reachable destination IP address. Costs
main processor time computing the FIB from the RIB of course, which
can be challenging in a large change event (e.g. a link loss).

Excepting source aggregation and terminal default routes, RIB
compression and reinjection is dangerous on multiple levels from
accidental leaks to connectivity loss and (in my opinion) should not
be done.

Bill Herrin

For hire.

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