[Olsr-dev] Thoughts about an ETX-FF-Metric plugin

[Henning Rogge]

On Thu, Jun 19, 2008 at 20:33, Markus Kittenberger
<(spam-protected)> wrote:
>> Maybe we can teach olsrd to send a "I'm switching off" packet before
>> it shuts down. This way the neighborhood has a chance to see the route
>> loss coming.
>
> a real packet special packet type, or just an hello with damn bad lq values
A Hello without any neighbours in it... something like "Hello, I don't
know ANYONE".

>> As long as the "clear information" timer is shorter than the "drop
>> route" timer this should be no problem.
>
> i wanted it the other way round,..
> do not use for routing fires earlier  (30 seconds after the last packet or
> earlier (4x hello interval)) (it may also stop hello timeouts, and further
> changes to the lq istory)
> much later (5 minutes or later) the history is deleted
Hmm... would require some changes in the link_set, but should be possible.

> would be no problem if the device announces its reboot,.. (stopping all
> neighbours from doing any further hello timeouts, modifing the history
> without receiving packets)
there is a chance that the neighbours don't get the package.

> how long does an started olsr needs currently before he has routes, 30
> seconds?
Depends on the timing... you need at least two hello intervals until
you have a symmetric link to a neighbor.

After this it just depends how fast you get the TCs of the other nodes
(might take a little bit time with activated fisheye mode).

> ok fine (i did forget this), replace 95% with 80% and think over it
> again,..
> but in fact its irrelevant that with 95% loss this link wouldn`t be used
> sometimes (when its lq is low enough)
the 10%/0.1 value can be chosen by the link metric plugin, so changing
this is no problem.

> what disturbs me ist that it will take substantially more time for an dead
> link to drop from ETX 1.0 to an e.g 4.0 (LQ 0.25 NLQ 1.0) (at >= 4 for
> example an alternative route would be used)
> than for an link with suddenly 85% loss, which can be nearly twice as fast
> (#), because NLQ will drop too, so with an LQ of 0.5 and nlq of 0.5 ETX 4.0
> is reached
Olsrd has a "quickstart" feature so that a link can get to a "good etx
value" fast... more a psychological thing. ;)

> # and maybe in relity more than twice as fast as it doesn`t have to wait on
> hello timeouts

?

Henning

-- 
"Wo kämen wir hin, wenn alle sagten, wo kämem wir hin, und niemand
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Marti)