Re: maximum ipv4 bgp prefix length of /24 ?

[Nick Hilliard <nick () foobar org>]

William Herrin wrote on 02/10/2023 08:56:
> All it means is that you have to keep an eye on your FIB
> size as well, since it's no longer the same as your RIB size.

the point Jacob is making is is that when using FIB compression, the FIB 
size depends on both RIB size and RIB complexity.  I.e. what was 
previously a deterministic 1:1 ratio between RIB and FIB - which is 
straightforward to handle from an operational point of view - becomes 
non-deterministic. The difficulty with this is that if you end up with a 
FIB overflow, your router will no longer route.

That said, there are cases where FIB compression makes a lot of sense, 
e.g. leaf sites, etc. Conversely, it's not a generally appropriate 
technology for a dense dfz core device.  It's a tool in the toolbox, one 
of many.

Nick