On Wed, Jul 2, 2014 at 8:22 AM, Juliusz Chroboczek <[email protected]> wrote: >>>> Regarding Z3 and RTT, you're right, it's not exactly clear. The current >>>> implementation of Z3 applies the diversity factor *after* all other costs >>>> are computed, included the one induced by babel-rtt. > >>> Huh? RTT and Z3 work at completely different places -- RTT tweaks the >>> cost computation, while Z3 changes the announced metric. > >> And we've just demonstrated that it is confusing, even to the authors >> of the IDs. > > Don't blame Baptiste, it is a difficult topic. There's good reason why > we're the one of the only production-quality protocols in the world that > support hybrid metrics. (There's IGRP, not sure about IS-IS.) It might > be interesting to write up everything we've learnt on the subject, but > that's more work than just an off-the-cuff comment on a mailing list. > >> Secondly, I was also hoping for an extended example of why diversity helps >> on longer paths as per my first email. > > I've added a second example. Is there anything else you had in mind?
Well, showing that performance falls off 1/2,1/3,1/4 (or is it 1/2, 1/4, 1/8?) as the number of interfering links on hops grows by 2,3,4 is a good thing to beat the shortest path ethernet-thinking-only people over the head with. Secondly, "When routing data from A to F, the route through B and C has two interfering links: two packets sent by A and C at roughly the same time will collide, and both will need to be resent. Again, no such issue arises with the route through D and E." This is true in the case of the hidden node problem, somewhat true in the case of adhoc, and not true in the case of an AP/sta. In the latter case especially, packets transiting in each direction are scheduled, not "colliding". The net loss in throughput is still enormous, have a paper around here somewhere on that... While I'm at this, a long standing bug in either the kernel or babel or both has been in determining the channel in the case of a bridged, or ap-mode connection. let me start another thread... > -- Juliusz -- Dave Täht NSFW: https://w2.eff.org/Censorship/Internet_censorship_bills/russell_0296_indecent.article _______________________________________________ Babel-users mailing list [email protected] http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/babel-users
