On 8/11/15, 5:17 PM, "homenet on behalf of Juliusz Chroboczek" <homenet-boun...@ietf.org on behalf of j...@pps.univ-paris-diderot.fr> wrote:
>> I am interested to learn what people think about whether equal-cost >> multi-path routes are needed in homenet. Given the previous discussion >> about parallel wireless links - which I know I have in my house and >>can't >> use - I've been wondering if these have been considered. > >As Toerless noted, source-specific routing combined with something like >MP-TCP gives similar effects to ECMP. One of the requirements of homenet is that you don’t modify the hosts so MTCP is not an alternative to ECMP. Thanks, Acee > Clauz from the Ninux project gave >a talk at Battlemesh with his experiences with such a setup, however, and >the conclusion was that in his particular network he couldn't get it to >work well enough to be useful for his particular application (VPNs to >a central server). > > https://www.youtube.com/watch?v=ztVogLI_ZJs > >(That was a great talk, by the way. We need more talks about what people >were unable to get to work, talks about successes are boring.) > >As to ECMP itself -- in a wireless environment, it must be done with care. >If you have two parallel links at the same radio frequency, you will get >collisions between the two subflows, which will get you worse performance >than what you'd get by using a single subflow. So your routing protocol >needs to be able to distinguish between interfering and non-interfering >routes, and only do ECMP on non-interfering subflows. > >In the particular case of Babel, this means that in order to efficiently >do ECMP over wireless you need to use the "Babel-Z" extension [1], which >propagates interference information in order to make better routing >decisions in multi-radio meshes. I've been refraining from mentioning >this extension on this list, since I've repeatedly been told that meshy >things are out of scope for Homenet. > >[1] https://tools.ietf.org/html/draft-chroboczek-babel-diversity-routing > Note that this extension is not frozen yet, I am planning > a backwards-incompatible change before I submit it for publication as > an RFC. (The TLV format will stay, but the interpretation of some > values will change; existing implementations will not be impacted.) > >Babel does not do ECMP yet (it does do feasible successors, of course). >If there's interest, and somebody willing to do some testing for me >(empirical data only, please), then I think I could conjure something up >pretty quickly. > >-- Juliusz > >_______________________________________________ >homenet mailing list >homenet@ietf.org >https://www.ietf.org/mailman/listinfo/homenet _______________________________________________ homenet mailing list homenet@ietf.org https://www.ietf.org/mailman/listinfo/homenet
