On 08/13/2012 08:18 PM, Esteban Municio wrote:

Hi all

I'm asking myself if should be possible change the actual metric(TQ) in batman-adv or if there is a tool to configurte it.

We are deploying a rural mesh network where the nodes generally will be static in the same place, but maybe the links beetwen the nodes will have a unnestable bandwidth.

So we are looking for what protocol (with any plugin) is more efficient for our network.

Batman-adv have TQ like metric, but we would like that the nodes route the traffic priorizing the links with best bandwith available instead the links with best QoS. That is because finally, all the links tend to have ETX=1 at the expense of reduce de bandwidth(reducing the modulation and codification scheme in order to reduce looses), so the nodes route always for the shortest path...

Is there any solution for this?Do you recommend us change to another mesh protocol(OLSR+plugin) or another "static" protocol(ej: OSPF)? It is possible configurate batman-adv to get the fastest route instead the safer? Or maybe I am not understanding something...Am I proposing a fool thing?

At QuintanaLibre we experimented quite a bit with this and came to the conclusion that setting a high multicast rate is a good solution to "force" batman to only use good (in terms of bandwidth) links.

If you set the mcast_rate high, for example (OpenWRT):

config 'wifi-iface' option 'device' 'radio0' option 'mcast_rate' '54000'

then low bandwidth routes will effectively become invisible to batman.

We are using this setup in a semi-rural network, 3.5Km wide with 15 active nodes (as of today) and it works very well.

By doing this you loose redundancy, so if you have a node with only one high bandwidth link and that link fails, the node won't have other routes to use. In our experience this is OK because the alternative low-bandwidth routes that are available if mcast_rate is very low are not of much real use.

Cheers, NicoEchániz