[Olsr-dev] gateway selection

Ferry Huberts (spam-protected)
Wed Jul 25 11:08:49 CEST 2012

Hi guys,

While reviewing the gateway code, I encountered something that works
differently than Teco and I expected so we would like to change it.

The problem: the current gateway selection code doesn't take the
advertised uplink/downlink speeds into account, it only looks at the tc
path cost (sum of ETX-link costs).

The result of the current code is that the 'nearest' gateway is
selected. We would like to change that to 'nearest fat pipe'.

'nearest fat pipe' is a bit fuzzy so we would like to propose the

- We calculate a new path cost of

     new_path_cost = (1 / (uplink + downlink)) + (tc_path_cost / 4)

   (uplink and downlink in Mbps)
   (the 1 and 4 are weighing factors and we can make then configurable)

- Gateway selection is done based on new_path_cost

PS. in this we assume that tc_path_cost=1 signifies that the WLAN speed 
is reasonably good, say 4Mbps (but if that's different then we can tune 
it with the weighing factors)

Ferry Huberts

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