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

Adam Thompson athompson at
Mon Oct 24 15:46:26 UTC 2022

I can't believe that never occurred to me in all the time I was doing that, 'way back when...  <facepalm>
Thanks for pointing that out!

Adam Thompson
Consultant, Infrastructure Services
100 - 135 Innovation Drive
Winnipeg, MB R3T 6A8
(204) 977-6824 or 1-800-430-6404 (MB only)
Chat with me on Teams: athompson at

> -----Original Message-----
> From: NANOG < at> On
> Behalf Of Brandon Martin
> Sent: October 21, 2022 4:30 PM
> To: nanog at
> Subject: Re: any dangers of filtering every /24 on full internet
> table to preserve FIB space ?
> On 10/20/22 17:50, Adam Thompson wrote:
> > Alternately, a valid technique is to have a default route AND a
> partial BGP feed (a filtered full feed is by definition a partial
> feed).  That helps optimize outbound routing a little bit, you still
> get the advantage - mostly - of multiple inbound carriers; but you
> still have to pick one carrier to do the heavy lifting for you.  And
> you are paying them to route for you, so that's not an unfair
> shifting of the routing burden, unlike relying on covering routes.
> Note that this approach does NOT provide any redundancy, unlike
> having full BGP feeds.
> As a note, you can get redundancy (but still none of the best-path
> advantages of having multiple transits) by asking your transits to
> originate default in their BGP feed and then selectively accepting
> it.
> You can either ECMP it or pick priority with localpref.
> You need multiple full-view transits for this to work, though.
> --
> Brandon Martin

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