> Hi, I was wondering what is the best way to enable the RTT metric with > sensible defaults. It looks like max-rtt-penalty is the option that turns it > on. What is a good value to set this at starting out?
Yeah, the RTT metric is fiddly. For very good reasons -- it's an intrinsically unstable metric (it contains a feedback loop). I suggest you have a look at Section III.D of https://arxiv.org/pdf/1403.3488.pdf The most important parameters is rtt-max. It should be configured as a sufficiently large value, but small enough that the latency of highly congested bottleneck links is higher than rtt-max. The default value of 120ms works well in the global-scale overlay networks we've experimented with. Rtt-min and max-rtt-penalty don't matter much -- if rtt-max is chosen wisely, the algorithm will be reasonably stable whatever the other values. Rtt-min should be a value slightly larger than the latency of completely uncongested low-latency links; the default value of 10ms should be fine for most applications. max-rtt-penalty determines how much high-latency links are penalised; any value between 128 and 384 should yield decent results, I suggest starting with 197 (which happens to be a prime number). -- Juliusz _______________________________________________ Babel-users mailing list Babel-users@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users