[Olsr-dev] Strange ignored packets problem

Ignacio García Pérez (spam-protected)
Fri Jul 20 11:28:29 CEST 2007


Hi,

I have a test setup of 7 nodes deployed in a 1 sq. km urban area.

The net is 10.0.0.0/8, nodes are numbered 10.1.1.10, 10.1.1.20,
10.1.1.30 and so on.

The broadcast address is the olsrd default: 10.255.255.255.

 From a node, olsrd sees HELLO/TC packets from the nodes with a good
connection, but seems to see NO PACKETS AT ALL from nodes to which I
know it has a poor (BUT USABLE) connection.

Then, if I start tcpdump, olsrd suddenly starts seeing packets from
those nodes (with an expected 25% or so packet loss).

It looks like the radio card discards those packets when it is not in
promiscuous mode (which is the side effect of running tcpdump AFAIK).



When I change the setup to use 255.255.255.255 as broadcast address, no
packets are ignored.



Any idea about what may be the explanation of this behaviour?



Regards.





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