Babel RTT mechanism [Was: [RESEND PATCH v3] Babel: allow choosing link quality estimation] algorithm]

[Nick Cao]

I think it is the intended design. Link quality is about packet losses, 
while RTT is about, well, RTT, they cover different characteristics of 
the link, which should all be taken into account for metric calculation.
And babeld the reference implementation also allows enabling link 
quality estimation and the RTT extension at the same time, matching the 
current behavior of bird.

On 11/8/23 11:44, Ondrej Zajicek wrote:
> On Sat, Oct 28, 2023 at 09:24:56PM -0400, Nick Cao via Bird-users wrote:
>> Resend of the patch in http://trubka.network.cz/pipermail/bird-users/2023-June/017058.html
>>
>> ETX link quality estimation algorithm is useful for link types other than wireless,
>> especially when using babel with tunnels where packet losses do occur.
> 
> Hi
> 
> I looked at your patch with intent of merging it, i like a separate
> option for selection of dynamic metric algorithm, but i noticed that i
> misunderstood how recently added RTT mechanism interacts with the rest.
> 
> I thought we have three alternative link quality / metric estimation
> algorithms:
> 
>   - fixed (k-out-of-j)
>   - ETX
>   - RTT
> 
> But in fact RTT is independent metric, which is added on top of fixed/ETX
> metric.
> 
> Is this intentional? Does it make sense?
> 
> (This is mainly a question for Toke or Juliusz)
>