"Tactical" /24 announcements

Mark Tinka mark at tinka.africa
Sat Aug 14 05:56:51 UTC 2021

On 8/12/21 19:30, Nick Hilliard wrote:

> it also causes non-deterministic fib resource consumption. On most 
> edge deployments this won't matter, but it wouldn't be hard to cook up 
> a topology that could fail in interesting ways.  Overall fib 
> compression is a net win, but you need to be careful with it.

We only needed it on boxes with a small FIB, to begin with. We don't use 
this on large routers with millions of FIB slots to spare.

The challenge on small boxes is that at some point, even with the FIB 
filtering, you will run out of FIB slots, and then weird things start 

At that point, dumping the box and going for something larger (say, 
dropping a 20,000 FIB box and going for a 256,000 FIB box) is your only 
real option. It's still cheaper than a large box with lots more FIB, and 
you can continue the benefits of FIB filtering without causing weird 
problems in the network.


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