Re: [B.A.T.M.A.N.] [B.A.T.M.A.N.A.D.V] Deploy batman-adv using Station - Access Point mode?

[Antonio Quartulli <antonio@meshcoding.com>]

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Hi,

On 11/03/14 09:06, Le Tran Dat wrote:
> For example: What I am trying to do right now is to connect those
> devices by using Station <-> Access Point mode. But I have no ideas
> how the OGM message transmit between the Mesh Node so I worry that the
> Station <-> Access Point can not take advance of batman-adv.
> 

What you have to keep in mind is that everytime if a generic node A
receives an OGM where the Ethernet MAC address is the same as the
originator address then A thinks that there is a direct link between
itself and the source (simplistic explanation).

Therefore, to prevent the nodes from making wrong assumptions, you have
to enable the isolation on the Access Point.

If you don't do so then you can end up in the following situation:
1) STA1 sends an OGM as broadcast packet
2) the AP rebroadcasts such packet as per 802.11 standard (to ensure
that all the associated STAs can receive it)
3) a generic STA2 receives the OGM and erroneously thinks to be directly
connected to STA1, while this is not true because the packets must
travel through the AP[1].

However, even if the isolation makes batman-adv work reasonably you will
not have a nice setup because you cannot exploit direct links between
nodes that may hear each other due to the AP-STA constraint.

Moreover you need to decide which node has to act as AP and which as STA
before deploying them, thus limiting the "dynamic part" of the mesh network.


I hope this clarified the problem.


Cheers,


[1] you could have direct links if you are use TDLS, but most of the
drivers out there do not implement it.

-- 
Antonio Quartulli


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