[Olsr-users] Problems with OLSR

Gian Maria Giani (spam-protected)
Tue Sep 18 19:17:51 CEST 2007

The whole network contain 10 nodes in fixed positions, in outdoor
environment, using olsrd v.0.4.10. Each node has about 3 neighbours, and
the maximum distance between nodes is 3 hops. The problem we experienced
is that routes are not stable.


This seems related to the fact that some neighbours are listed as
non-symmetric (they appear as symmetric for some moments, then appear as
asymmetric, then again as symmetric). The percentage of lost packets
over these asymmetric links, however, is 0% in both directions. In the
past weeks we have made several tries (modifying the validity and
emission time of Hello and Tc messages, using link quality and
hysteresis, etc), but the routes are still unstable using these


We have then decided to make further tests with a subset of this
network, with only three nodes. The situation in this case is better,
but routes are still *not* stable even in this small network. We
observed the routes for about 20 seconds each time. With a total number
of 68 observations, routes have been changed 10 times, which means 14.7%
of the times. When we ran ping among nodes the percentage of lost
packets is 0%, but the round trip time varies from 1 ms to 45 ms.


Attached to this message you can find the output of commands iptable, ip
and iwconfig on the three nodes, as well as the contents of the
olsrd.conf file. A few small notes: we have copied the *current*
contents of the olsrd.conf file but, as mentioned previously, we have
already tried different configurations, including LQ. The network nodes
are Linux boxes using a small Linux image derived from OpenWrt, where
only a few packages are installed and sometimes with limited options (in
particular, this is relevant for the ip package, as you can see in the
attached text files).


In this phase of our work, we would like to find measures for improving
link stability, e.g. by using directional antenna, higher antenna gain,
better interference protection, etc, but staying with olsrd 0.4.10. Do
you have any hits on how to achieve high link stability, including both
hardware and software measures? What is the main reason for the above
described link instability problem?


Thanks a lot in advance.


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