[Olsr-dev] Freifunk Testing

elektra (spam-protected)
Sat Jun 14 22:47:01 CEST 2008

Hi -
> btw: Is there a reason for an TC Interval of 2 at an HELLO Interval of 5? that 
> would be 2 TCs before the linkcost of a link could change...
there is. This is to avoid routing loops even when links are saturated 
with payload traffic. Not all TC updates are likely to come through 
under these circumstances, so redundancy helps here. (But even when 
sending TCs twice as frequently as Hellos,  Olsrd did loop occasionally 
when we were testing it at the Meraka 'Massive Mesh' grid under high 
payload.) To get entirely rid of routing loops, TC redundancy has to be 
even greater. But the resulting protocol overhead is much more severe 
then occasional routing loops that persist for a couple of seconds. This 
is a limitation of the protocol design.

If you are not using Fisheye TC redundancy is of course very bad for a 
large scale network.

Btw: There should be an option to disable the MPR algorithm completely. 
It is superfluous anyway for Freifunk-like configurations since Wizard 
of OS 2004. Setting MPR redundancy to 7 in the config is just a dirty 
hack to get rid of the negative effects of  MPR selection and the 
problems that are growing out of it.

cu elektra

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