Hi Folks
I've been playing with B.A.T.M.A.N advanced for a few weeks now.
One of the scenarios where we might want to use it is nomadic vehicles. Each vehicle has a wifi radio which is used to build a mesh between the vehicles when the vehicles are parked together at a location. I said the vehicles are nomadic. By that i mean they tend to stay in one place for a while, and then move on. They can move individually, or in groups. For the moment we are not interested in meshing while on the move.
I've run into a "problem" when one vehicle/node moves away from the rest of the vehicles/nodes. It is taking a long time for the mesh to realize the node has gone and rebuild the mesh. With a 500ms orig_interval in our little test network, pings get lost for an average of 26 seconds. The variation is great, sometimes it reroutes in 10 seconds, sometimes in 50 seconds.
So i want to improve this. The first thing i did was make some plots of the tq_avg value, as shown in /proc/net/batman-adv/originators. I look at one particular originator and plot the different tq_avg values for the list of neighbors. Attaches is a png image showing this.
I was surprised to see that its unstable and oscillating. The different tq_avg values mostly oscillate together, as shown in the figure, but i've also seen cases when they oscillate 180 degrees out of phase. In that case, the routing flips on the cross overs.
Is this normal? Is it expected behavior?
Has anybody worked on making re-routing around disappears nodes faster?
Thanks Andrew