[Olsr-users] INFINITE cost in all links

Henning Rogge (spam-protected)
Mon Jul 28 08:07:48 CEST 2014

On Fri, Jul 25, 2014 at 12:11 PM, Antonio Anselmi
<(spam-protected)> wrote:
> Hi all,
> I'm facing an odd problem that recurs randomly, without any user
> intervention, at different times on a single-gateway network.
> Suddenly, all the links of the gateway node have their NLQ values equal to
> zero and the respective LQ values greather than zero, so every link has an
> INFINITE cost -> olsrd route table is empty -> ip main route table is empty.
> Just because all NLQ values are zero, it seems that the nodes do not
> receive/hear olsrd packets from the gateway, but , at the same time, the
> gateway itself continues to receive and process packets sent by the other
> node (LQ values change in time).
> In this situation, I logged to the gateway node and run the command 'tcpdump
> -vv -ni wlan0-1 port 698' (wlan0-1 is the adhoc interface) to inspect the
> way olsrd was working.
> As supposed:
> 1) the gateway had stopped transmitting olsrd packets but continued to
> receive and process olsrd packets sent by the other nodes
> 2) olsrd route table and ip main route table were empty and the gateway does
> not ping any other node
> 3) the topology seen by the gateway have no node reachable
> 4) at layer2 the neighbors are all associated (iw dev wlan0-1 station dump)
> so adHoc beacons travel
> Stopping and restarting olsrd does not fix the stalemate as well as manually
> populating the ip main route table. Obviuosly, rebooting the node all goes
> right ...untill the next olsrd stale.
> I'm wondering:
> 1) Why all links go to INFINITE cost? (A loop caused by LQ mechanism?)
> 2) may be the case that the gateway try to transmit olsrd packets, but since
> its route table is empty, no packet reach the adHoc interface
> (loop inside the gteway) ?
> 3) since the TC-LQ packets sent by the nodes (and received by the gateway)
> do not show the gateway (NLQ = 0) why these packets reach the gateway? Nodes
> should have no route to the gateway since they do not hear it!
> 4) and... the all_INFINITE_costs situation (as well as the empty routing
> tables) is a "cause" or an "effect" ?

NLQ infinite most likely means that the other side cannot hear you,
but you can hear the other side.

Can you check on the gateway with the txtinfo command?

Henning Rogge

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