[Olsr-dev] [PATCH v3 1/1] smart gateway: add threshold configuration parameter

Teco Boot (spam-protected)
Thu Dec 15 11:43:19 CET 2011


Op 14 dec. 2011, om 23:26 heeft Markus Kittenberger het volgende geschreven:

> On Wed, Dec 14, 2011 at 8:28 PM, Teco Boot <(spam-protected)> wrote:
> 
>> i asume trying to have a default value that really suits highly mobile and static city-meshes is impossible,..
> 
> What about trying to be smart: when candidate is far better than current, change fast (but not to fast). So we count the elections of a better candidate, and switch based on better path and duration it is the best.
> 
> no bad idea (if i got it right), but might need more parameters to define this smartness,..
For sure more thoughts.

> e.g. a slow and a (lower) fast-SGW-Threshold 
> and a slow-SGW-Threshold-duration value,..
> 
> and if a new gateway is fast-SGW-thresh better olsrd should switch "instantly"
> but if new gateway is only by slow-SGW-thresh better, olsrd shoudl switch only after it is/was always better for a full slow-SGW-Threshold-duration,..
Yes:
 - do not switch if better-costs > slow-threshold * current-costs
 - do fast switch if better-costs <= fast-threshold * current-costs   # fast means: at least candidate is selected twice in succession
 - lazy for other costs, something like:
   (1 - (slow_threshold * current_costs - better_costs) / (current_costs *  (slow_threshold - fast_threshold))) * sgw_threshold_duration
   And something with sgw-timer-interval
My suggested defaults:
      SmartGatewayFastThreshold  0.3
      SmartGatewaySlowThreshold  0.7
      SmartGatewayMaxSwitchTime  180
SmartGatewayFastThreshold must be less or equal to SmartGatewaySlowThreshold.
If SlowGatewayFastThreshold is zero, there is no switchover.
And some div by zero checks....
 
> but such smart/configuration/code "heavy" stuff, should imho really be a plugin!!
If almost everybody benefits, it is ok to put it in the baseline.
Plugin is great for special cases. E.g. set the up- and download rates. Or set up multiple tunnels and adjust routing.

Teco
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