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

Brandon Martin lists.nanog at
Fri Oct 21 21:30:28 UTC 2022

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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