[Olsr-dev] Modification to the MPR selection algorithm

Ayan Roy-Chowdhury (spam-protected)
Wed Jun 9 20:13:56 CEST 2010


** Apologies if the issues raised below have been previously addressed 
in the mailing list - we have missed them if so. **

We are implementing the Stable Path Topology Control (SPTC) algorithm
which selects the MPR set based on some link stability metric, instead
of the hop count. So the shortest path from a source to destination uses 
links based on the stability metric, instead of the hop count.

To achieve this, we are modifying the MPR selection algorithm in the 
OLSR implementation. The metric we use is ETX.

Our understanding is that, when ETX is used, the MPR set is computed in
void olsr_calculate_lq_mpr(void) in lq_mpr.c, and not by the functions
in mpr.c. -- Is this correct?

We have not gone through all the source code - would greatly appreciate
if we can be directed to the relevant sections that will {affect | be 
affected by} any changes to the MPR selection algorithm.

Also, from reading the default config file olsrd.conf.default.full, it 
seems that the OLSR MPR optimization does not work in v0.6.0:
......
......
# TC redundancy
# Specifies how much neighbor info should be sent in
# TC messages. Because of a design problem in the 0.5.x
# dijkstra implementation this value must be set to 2.
# 2 - send all neighbors
# (default is 2)
.......
# MPR coverage specifies how many MPRs a node should
# try select to reach every 2 hop neighbor. Because of
# a design problem in the 0.5.x dijkstra algorithm this
# value should be set to 7.
# (default is 7)
.......
# Link quality level switch between hopcount and
# cost-based (mostly ETX) routing. Because of
# a design problem in the 0.5.x dijkstra algorithm this
# value should not be set to 1.
# 0 = do not use link quality
# 2 = use link quality for MPR selection and routing
# (default is 2)
......
......

Is there any patch for the above?

Thanks and regards,
Ayan






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