[Olsr-users] multiple Gateway selection problem

Soumendra Nanda (spam-protected)
Mon Jun 25 19:21:16 CEST 2007


I have a ip v4  mesh network with multiple gateways to the Net that do
NAT using OLSR 0.4.10.

If you consider the scenario in Fig 13.1 of Tonnesen's MS Thesis
http://www.olsr.org/docs/report_html/node190.html#gateway-test1   ...
I recreated the same setup.

In my mesh all nodes use link quality options et to 2.

What I notice is that a mesh node X (not directly connected to the Net
but within range of two gateways) keeps changing its default gateway
even in a static stable network.

Say is a gateway (GW1) and 192.1681.1.20(GW2) is another
gateway. I notice every 30 seconds or so node X will change its
default gateway for from to for 2 to
3 seconds and then go back to As  a result all TCP
connections from X or through X to the Net are lost most of the time.

Is there any way to prevent this sort of oscillation in a static
network?  Is there some parameter I need to adjust?

I read about the ip in ip tunnelling option in the thesis but  is
there something simpler and more transparent since that requires an
explicit gateway to be specified... all I think that is needed to
prevent this  in this situation, is to make OLSR select historically
stable routes to the gateway and append additional routes with a
higher metric to act as backup routes to the Net.
For a more mobile scenario, I am not sure what is the right solution
to allow roaming nodes to maintain connectivity to the Net with OLSR.


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