[tor-relays] TCP CCA for Tor Relays (and especially Bridges)

[Felix]

Hi Matt

Am 2020-01-09 um 6:58 AM schrieb Matt Corallo:
> I’m sure this exists somewhere so this is more of a request-for-links, but what’s the current thinking on TCP CCA selection for Tor relays? While it has fairness issues (and reported long-tail issues for higher-latency links, though I can’t find good in-practice analysis of this), BBA should handle random packet loss much better than, eg, Cubic. This is likely less of an issue for western users, but many other parts of the world (especially China) see much higher packet loss due to regularly-overloaded links. I presume it is not good practice to change the default CCA for relays/bridges, but it seems BBA/BBAv2 would be a worthwhile experiment to see if it improves the browsing experience for non-western tor users.
>
> Matt

You can find a nice compare between loss less and loss based congestion
here [1].

It's difficult to say if one or the other are better in the use with
Tor. A single TCP connection between two Tor relays bundles multiple
circuits (data flows) which can result in very different needs for
congestion to connect end points.


[1] https://
heim.ifi.uio.no/davihay/hayes10__google_delay_based_tcp_conges_contr.pdf
--
Cheers, Felix