[B.A.T.M.A.N.] Change metric and priorize links with the best Bandwidth

[B.A.T.M.A.N.] Change metric and priorize links with the best Bandwidth

[Esteban Municio]

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?

Thanks you

Regards

-- 
Esteban

Re: [B.A.T.M.A.N.] Change metric and priorize links with the best Bandwidth

[Nicolás Echániz]

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