[Olsr-dev] LinkQualityMult problems in 0.5.6-r5

Mitar (spam-protected)
Sat Sep 5 13:29:27 CEST 2009


On Sat, Sep 5, 2009 at 12:38 PM, Henning Rogge<(spam-protected)> wrote:
> Am Samstag 05 September 2009 12:25:06 schrieb Mitar:
> The problem is it's practically impossible to manipulate the routing with
> lqmult correctly unless you are the administrator of ALL nodes in the net.
> Other users will see that their routing is strange (because of your changes)
> and will change THEIR lqmults to "correct" it... that's a game you cannot win.

I agree. I think current semantics of LinkQualityMult is problematic
as it changes link quality only in one direction. I think it would be
better if you (as an node owner/administrator) would be able to say
that you would prefer that ETX of (all or some) links to your node
would be (artificially) increased not by changing link quality (as it
is still good to know what is real link quality).

Or maybe oven better with ETX so that it would properly represent link
quality but to add another multiplier of "willingness" to be a route
(not to be confused with current OLSR willingness to relay control
data). So that OLSR would choose route based on ETX * "willingness".

This would then solve the problem of administrating diverse networks.
Like we could set this "willingness" on a VPN server to low and it
would not be necessary to play with ETX. And some other node which has
expensive to use interface would set "willingness" on that interface
to low to discourage setting route through it.

> Backup link is just a name for "don't use it unless it's the only way".
> Anything else should be handled by the routing metric.

And this "only way" mean 10% packet drop? 50%? 100%?

> MANETs (mobile ad hoc networks, Freifunk is a special case of this) do work
> because they use a sane routing metric on all nodes... and they use THE SAME
> routing metric. You cannot really change global behavior with local changes
> without lot's of problems for the rest of the network.

But they also work because of all diverse people with diverse reason
why they cooperate. And if somebody want to join a network but be just
a relay in a case of emergency it should be possible to setup this for
him. Currently only way is to set LinkQualityMult.

And it should be depended on if other nodes agree that his/her node is
just emergency node or not.

MANETs should work on a diverse range of equipment, platforms and people.


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