Blog de Flap

30/12/2005

Optimisation d’OLSR dans le cadre d’un réseau maillé (mesh network)

Filed under: Wifi — flap @ 17:21

Voici un massage envoyé par Thomas Lopatic, développeur du projet olsr, sur la liste de diffusion des utilisateurs. Il explique la portée de certains paramètres qui sont extrèmement intéressants…

Hi Karl,

You might want to try setting the HelloValidityTime parameter to a
higher than default value. In your case, with links there are two
mechanisms at work - (1) link detection and (2) link quality. The link
quality case is what you care for with the large window size. However,
in your configuration file you do not change the link detection
parameters. By default, every two seconds a node broadcasts a HELLO
message to announce its existence to its neighbours. The corresponding
configuration line would be "HelloInterval 2.0". In its HELLO messages
it also says "if you do not hear a HELLO message for six seconds,
consider me dead". The corresponding configuration line would be
"HelloValidityTime 6.0". So, if three HELLOs in a row are lost, then the
link is considered down, irrespective of the link quality window size.

So, what this all boils down to is that we recommend setting the
"HelloValidityTime" to "HelloInterval x LinkQualityWinSize", i.e. to use
"HelloValidityTime 120.0" on *all* nodes in your mesh. (Remember that
setting this value on node X influences the behaviour of X's neighbours,
i.e. if you set the validity time to 120 seconds on node X, all of X's
neighbours will consider the link to X existent as long as there's at
least one HELLO from X every 120 seconds.)

In this way, we guarantee that link detection will not remove a link
before link quality has had a chance to let it's link quality decay to
the worst possible case, which is that LinkQualityWinSize x
HelloInterval packets have been lost. So, basically, what we do is, we
switch off link detection and leave it all to link quality.

So, I'd recommend adding "HelloValidityTime 120.0" to your interface
configuration.

BTW, "HelloInterval x LinkQualityWinSize" is the default setting for
HelloValidityTime in 0.4.10, which is used if the user doesn't specify
anything else. So for 0.4.10 your configuration will work as is.

-Thomas

29/12/2005

Supervisez gratuitement vos sites web

Filed under: Sympa — flap @ 11:55

OZOOD Solutions nous propose gratuitement depuis sont site http://www.ozmonitor.net/ de superviser nos sites web. Pour cela, il suffit d’aller sur leur site, de créer un compte en référençant le site à surveiller et le tour est joué.

C’est un service intéressant qui permet de remonter des alertes afin de ne pas passer à cotés de problèmes d’accès…

28/12/2005

A propos

Filed under: Inclassable — flap @ 14:13

Peut-être bientôt une informations me concernant ici ;-)

Ouverture de mon Blog!

Filed under: Inclassable — flap @ 14:13

C’est pas une grande information, ok, mais c’est la première…

Ce site est hébergé chez ovh sur un 90plan (le même que www.mynetmemo.com).

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