[Olsr-users] Strange OLSR behaviour

[Mitar]

Hi!

We have connected a new node with directional antenna to one of our
nodes (which has an omni antenna) and on this node with omni antenna
VPN uplink currently does not work. Because of this we have discovered
really strange OLSR behaviour.

The central node is "fri" node (with omni antenna):

https://nodes.wlan-lj.net/nodes/node/fri

and it connects to three nodes "gerbiceva-49", "glinska-9" and
"stefanova-15-ii". Or better, those three nodes connect to it with
their directional antennas. "stefanova-15-ii" is this new node which
has rather flapping link because it uses wrong polarisation. The
problem is that those two nodes ("glinska-9" and "fri") are cut off as
the link from "stefanova-15-ii" is flapping. But all this while link
to "gerbiceva-49" is good: I have SSHed to "fri" node from
"gerbiceva-49" node and was able to normally work on it. At the same
time I have let running ping (with default packet size) in both
directions (between "fri" and "gerbiceva-49" nodes) and in few hours
there was just 4% of packet loss in both directions without any
periods of link loss.

But OLSR is adding and removing route to "fri" node all the time so
from network it is mostly unreachable. (I have to connect to it
directly from  "gerbiceva-49" node.)

Our current mesh topology can be seen here:

https://nodes.wlan-lj.net/nodes/topology

It is strange that sometimes route is removed and then topology is
drawn with "glinska-9" and "fri" nodes in the "air" - not connected to
the rest of the mesh but still drawn. While route between "fri" and
"gerbiceva-49" is not drawn. And at the same time ping normally works
between "fri" and "gerbiceva-49".

We use OLSR 0.5.6-r7 on nodes with such configuration:

AllowNoInt yes
UseHysteresis no
LinkQualityFishEye 1
LinkQualityLevel 2
LinkQualityAging 0.1
LinkQualityAlgorithm "etx_ff"
LinkQualityDijkstraLimit 0 9.0
FIBMetric "flat"
Pollrate 0.025
TcRedundancy 2
MprCoverage 3
MinTCVTime 500.0
NatThreshold 0.75

Interface "wl0"
{
  Ip4Broadcast 255.255.255.255
  HelloInterval 5.0
  HelloValidityTime 40.0
  TcInterval 2.0
  TcValidityTime 256.0
  MidInterval 18.0
  MidValidityTime 324.0
  HnaInterval 18.0
  HnaValidityTime 108.0
}

And tap0 interface has LinkQualityMult default 0.80 added. And yes, we
have the same IP addresses on all interfaces (so on "gerbiceva-49"
both tap0 and wl0 interface has the same address).


Mitar