Re: "Tactical" /24 announcements

[Jon Lewis <jlewis () lewis org>]

On Thu, 12 Aug 2021, Nick Hilliard wrote:

> Jon Lewis wrote on 12/08/2021 18:09:
> >  Arista.  They call it FIB compression.  They mention it's a trade-off,
> >  more memory and CPU utilization (keeping track of things) in exchange for
> >  being able to keep hardware that might otherwise be out of FIB space able
> >  to cope with full tables.
>
> 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.

Yeah...changes to the network could suddenly run such a box out of FIB 
resources, and you could easily be wrong when predicting how much longer a 
box has for it's "full routes" days...but the alternatives are "don't do 
full routes" or replace the box much sooner.
In that respect, it's somewhat remarkable that Arista even developed the 
feature.  "We can sell them newer hardware with larger FIB capabilities, 
or offer a software update that extends the life of the gear they've 
already bought."  What company chooses the latter? :)

----------------------------------------------------------------------
 Jon Lewis, MCP :)           |  I route
 StackPath, Sr. Neteng       |  therefore you are
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________