Re: [B.A.T.M.A.N.] B.A.T.M.A.N. port to ESP32

[Sven Eckelmann <sven@narfation.org>]

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On Montag, 8. Oktober 2018 18:43:37 CEST John Gorkos wrote:
[...]
> > This sounds wrong. You should not rebroadcast any OGM. You should
> > only rebroadcast from the best candidate. I'm wondering whether
> > this could cause issues. Or are you testing with a single
> > EspressIF and a single Pi only for now?
> I must have a misunderstanding of the BATMAN IV OGM mechanism.  My
> understanding is that ALL 1-hop (direct) neighbors will rebroadcast the
> heard OGM, and beyond that, only best-hop candidates.

Yes, single hop neighbors have special rules. But it is also important to 
check for the incoming+outgoing interface [1].

[...]
> So, to be clear, I'm working on BATMAN IV and not BATMAN V.  Based on
> the open-mesh docs, BATMAN V networks don't rebroadcast OGMs but instead
> use the Echo Location Packets.  Am I reading that wrong?

Yes, you are wrong. ELP are used in a link-local context (detecting neighbors 
and announcing itself to neighbors). OMG2 are used to inform the complete 
mesh.

> If there's a
> compelling reason to move to BATMAN V, I'd be happy to take a look at
> it.

B.A.T.M.A.N. V is using a different metric. IV is using one which is basically 
packet loss based for direct neighbors and V is using the expected throughput
for direct neighbors. Unfortunately, the ELP documentation [2] in the wiki is
outdated [3].

Kind regards,
	Sven

[1] https://git.open-mesh.org/batman-adv.git/blob/6f6cc4f54909127b236069207fe5691d31c29b24:/net/batman-adv/bat_iv_ogm.c#l1411
[2] https://www.open-mesh.org/projects/batman-adv/wiki/ELP
[3] https://www.open-mesh.org/issues/363

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