[Olsr-dev] invalidate node links

Giovanni Di Stasi (spam-protected)
Fri Sep 30 10:49:53 CEST 2011

 Hi everyone,

I would like to receive some advices regarding an experiment we are currently performing aboud channel assignment algorithms. The scenario is multi-radio.

The channel assignment algorithm (centralized) triggers at a certain point the change of channels of most of the interfaces of nodes. It may happen that a neighbor which was reachable through one interface, after the change,  becomes reachable through another interface [1]. The experiment we are doing shows an interruption of approximately one minute before the TCP connections we had established are able to return to their full speed.
This is due (I noticed that by taking a look at the Olsrd logs) to the time Olsrd needs to drop the old route (on the old interface) and use the new one (on the new interface).
We would like to speed up things a little bit. The first attempt we think  to do is to reduce the Hello and TC Intervals. This would speed up the change but will imply greater overhead. First results however show no improvements.
A different solution would be to discard all the links departing from the interface of which we have changed channel. If we change the channel of an interface, it means that all the links departing from that interface are (probably) no longer good, so it is good to drop them and start using new links (possibly just after the first hello packet is seen, so to regain rapidly connectivity). Do you agree on this solution?   If that's the case, how can I tell to Olsrd to drop all the links from a certain interface?

Thanks a lot,

[1] suppose two nodes each with two interfaces, the one set on channel 1 and the other on channel 2. After the channel change the first node starts using channels 3 and 4 and the second channels 4 and 3.

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