[Olsr-dev] Too many OLSR messages...

Henning Rogge (spam-protected)
Sun Aug 9 09:15:32 CEST 2009


I had a huge cleanup session for the OLSRd development code yesterday and 
discovered something BAD... something that might go back to the original OLSRd 
code from the diploma thesis of Andreas Toennesen (I tracked it back to the 
initial checkin in the olsr-ng mercurial repository in September 2004).

OLSRd has the timing configuration for HNA/MID/TCs for each interface, which 
does not make really sense because this messages are flooded, so interfaces 
"configured slow" will still get messages from faster interfaces through 

The really bad thing is that each of the messages send out through the 
multiple interfaces has it's own message sequence number !

So OLSRd is NOT sending a common flooded information through all of it's 
interfaces, it's sending different messages, sometimes with slightly different 
content through the interfaces. This means that a node with 4 interfaces 
produce FOUR TIMES as much TCs/MIDs/HNAs per timeslot than anyone thought, 
which are a horror for duplicate detection and network load.

The sollution in the development branch is to pull the timing parameters into 
the global section (out of the interfaces) and have one global timer for TCs, 
one for HNAs and one for MIDs which send messages through ALL of the nodes 

Do we want this change backported into the stable branch ? I think yes. But 
how shall we do it without breaking too much stuff ? Do you think it's enough 
to have a "sane" TC/MID/HNA timing default and just ignore the settings in the 
interfaces ? All webinterfaces and olsrd.conf are just designed for the 
interface parameters, so the configuration change is not trivial.

What do you say ?

Henning Rogge
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