Re: [B.A.T.M.A.N.] batman-adv: Force line topology

Sven Eckelmann
2015-06-13T13:58:35Z

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On Friday 12 June 2015 13:31:54 Carlos Meralto wrote:
> Hello, I am developing my thesis on mesh networks. And I'm currently
> doing some tests with batman-adv.
> So my question is:
> I need to create a line topology. For example:
> A-> B-> C-> D
>
> Of all the options I tried, I could not find a solution to do this
> https://lists.open-mesh.org/pipermail/batman/2012-September/008019.html
> https://lists.open-mesh.org/pipermail/batman/2011-July/005169.html
>
> I can not use the ebtables because I am using the wlan0 interface. And
> when I try to create a bridge on the interface (wlan0) gives me an
> error.
>
> root@OpenWrt:~# batctl if del adhoc0
> root@OpenWrt:~# brctl addbr bridgeWlan
> root@OpenWrt:~# brctl addif bridgeWlan adhoc0
> brctl: bridge bridgeWlan: Operation not supported

You can patch the driver to allow this (it is just a simple check which
disallows it in most drivers... or actually in wireless core [1]). But you
should make sure that you still use the same mac addresses for vif + bridge
and don't end up with 4 address packets.

> There is already a way to force a topology in batman-adv?

No. There were only different solutions (not acceptable for the linux kernel)
which did this directly in batman-adv. A very prominent (and easy to find)
solution was from Martin [2]

The idea behind batman-adv is that it finds paths and thus automatically
creates a good virtual topologies.

> I'm blocked with no solution.
>
> Thanks in advance.

I don't know why you want to use wlan and you also don't explain it in your
mail. You could for example also use emulation + vde2 [3] since you already
try to emulate a setup which is not there in reality.

Kind regards,
Sven

[1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/net/wireless/core.c#n1021
[2] http://git.open-mesh.org/batman-adv.git/commit/b6b01487d43ca82a53e61b3651506082a280f422
[3] http://www.open-mesh.org/projects/open-mesh/wiki/Emulation

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