[Battlemesh] Session about multi-homed IPv6 mesh networks and auto-configuration

Dave Taht dave.taht at gmail.com
Tue Apr 19 18:48:37 CEST 2016

On Tue, Apr 19, 2016 at 9:40 AM, Ferry Huberts <mailings at hupie.com> wrote:
> On 19/04/16 18:23, Juliusz Chroboczek wrote:
>>> We need metrics in the homenet protocols to be able to handle this.
>> Homenet uses Babel for announcing reachability, which has metrics.
> Yes, but AFAIK there are no provisions for announcing exit link bandwidth.
> We really need something like that to be able to choose the best gateway to
> use. This becomes especially relevant in mesh scenarios where nodes might be
> multiple hops away.
> As an example: a mesh node is 1 hop away from an exit link with very little
> bandwidth, and several hops away from an exit link with a very high
> bandwidth. Depending on conditions it might be advantageous to pick either
> one or the other. This is only possible when we know BOTH the exit link
> bandwidth and the mesh metrics.

I prefer to think about it as a congestion problem. If that local link
is entirely unused, and that gigE link saturated, which would you

> This becomes somewhat less relevant when using MP-TCP. Not very much however
> when there are many exit links since you generally don't want to use many
> many exit links in a MP-TCP session, especially on a mesh.

Source specific routing pushes the choice of exit link to the
application, which I like a lot. http://arxiv.org/pdf/1502.02402.pdf
for mosh was quite lovely (did it ever make mainline?), and mp-tcp is
not required - IF we could push source address selection into the
application for regular tcp (or quic), in a browser, something much
like happy eyeballs would suffice.

>> Where Homenet is different from what you're used to is that it announces
>> all available gateways using source-specific routes, and hosts are
>> supposed to choose the gateway they use (by picking a given source
>> address).  See
>>    http://arxiv.org/pdf/1403.0445.pdf
>> Unless they snoop on Babel traffic, however, hosts have no information
>> about the metrics associated to individual prefixes.  Snooping on Babel
>> traffic is not difficult, but it is not defined by the Homenet
>> architecture,
>> since Homenet requires no host changes.
>> -- Juliusz
>> _______________________________________________
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> --
> Ferry Huberts
> _______________________________________________
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> Battlemesh at ml.ninux.org
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Dave Täht
Let's go make home routers and wifi faster! With better software!

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