On Sun, Oct 1, 2023 at 9:55 PM Jakob Heitz (jheitz) <jhe...@cisco.com> wrote: > my main point > is that FIB compression does not allow you to install a FIB with less memory.
Hi Jakob, The math disagrees. It's called "oversubscription," and we use it all over the place in network engineering. There are only a handful of route patterns that'd result in no compression at all. They'd have to be intentionally created, and that'd be a hacking challenge in and of itself. The patterns in question don't align with the distribution of addresses on the Internet. If you're at 80% FIB after compression, a compression transient could plausibly bump you to 85%. The odds of a natural transient bumping you to 100% are infinitesimal. If you try to run at 95% after compression... well, I'm sure someone will try it, but that's PEBKAC not compression's fault. FIB compression ranges from 30% in simple core scenarios to more than 90% in edge scenarios with advanced compression. Even keeping reasonable slack for transients, you're going to get some bang for your buck. 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. Regards, Bill Herrin -- William Herrin b...@herrin.us https://bill.herrin.us/
