[Olsr-dev] Using OLSR and avoid paths with the same cost. Is possible ?

ZioPRoTo (Saverio Proto) (spam-protected)
Mon Mar 15 16:02:04 CET 2010


Hello,

I'm using OLSR for something not usual.

I'm using OLSR to route traffic inside a VPN Overlay network. I'm
implementing a theoretical work to write a scientific paper, I don't
just need things to work, but I need to be exactly sure of what
happens in the network.

I have basically no packet loss on my VPN links, so all links are ETX
= 1. I don't use the hysteresis because I know that code is not well
tested. So I'm using the default configuration file shipped with
olsr-0.5.6.r8, basically specifing just the network interface where
olsr must run.

Now when a generic node "A" wants to send traffic to node "B" there
might be two different paths with extactly the same number of hops. If
all links are ETX = 1 it is like hopcount.
Now for my experiments to be rigorous I need to be extremely sure
about what path OLSR will choose to route the traffic, even if there
are some "same cost" paths.

To avoid "same cost paths" my idea is to use the LinkQualityMult in
the config to put a little "noise" in the links so that there are no
links with exactly the same cost. Using:

LinkQualityMult default RANDOM

Where RANDOM is a number very close to 1 (between 0.95 and 1.05), and
of couse this number is different in the configuration of every node,
I should have unique cost paths ...

Do you think this can work ?
Anybody has a better suggestion to solve this problem ?

thanks ! :)

Saverio




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