Thank you for the explanations. I now clearly understand the options better. This is probably a slightly more stupid question, but I'm not very familiar with metrics: A year ago you said [1] that bird had not yet implemented "hysteresis on metrics" and therefore `rtt-min 1 rtt-max 1001 max-rtt-penalty 1000` could be unfavorable or problematic. Has bird implemented this in the meantime? And what is the difference between hysteresis and `rtt-decoy`? [1] https://trubka.network.cz/pipermail/bird-users/2023-October/017216.html On Wed, 17 Jul 2024 20:41:52 +0200 Juliusz Chroboczek <jch@irif.fr> wrote:
Thanks for the quick answers!
What should I set rtt-cost/max-rtt-penalty to?
Max-rtt-penalty controls how much Babel will prefer routes with many links but low RTT to routes with few links but hight RTT. The default is fairly conservative, meaning that RTT has only a very small influence on routing. You should set it to 96*n where n is the maximum number of extra links that you're willing to take in order to avoid one high-RTT link.
You should probably set it to 400 or so, and start tweaking from there. The value used by Nexedi (5000) looks quite extreme to me.
As to rtt-decay, the default value should be fine unless you have a mobile network. Increase it in order to react faster to RTT variations, at the risk of route flaps every time the network has a hiccup.
-- Juliusz
-- Marek Küthe m.k@mk16.de er/ihm he/him