On Aug 14, 2012, at 4:02 PM, Adrian Dudau wrote:

> Hi everyone,
> 
> I have stumbled upon the following issue while trying to port the TinyOs Link 
> Estimator implementation onto a different platform. In the file 
> LinkEstimatorP.nc, there is a NeighborTable structure that holds the 
> up-to-date link quality information to all the neighbouring nodes. This table 
> is parsed and the corresponding eetx value is returned when the module is 
> asked the link quality of a specific node. My issue is the following: what 
> happens when the connection with a neighbour disappears? As the corresponding 
> RoutingTable seems to be updated only upon receiving a message from that node 
> (by calling updateNeighborEntryIdx() on the corresponding entry), the link 
> information seems to stick in the table and continue to be reported to the 
> caller even when they are not connected anymore. It seems like a too obvious 
> flaw, so I somehow expect that I'm missing something, though I can't see it 
> at this moment. So I appreciate someone else's view on this :)

This is more a question for -help, I'm moving it there.

The link estimator doesn't assume a particular beacon rate; it might receive no 
packets because the node has an excessively long beacon timer. The assumption 
is that if a node starts sending packets to the dead destination, then none of 
them will be acked, and these failed transmissions will then update the link 
estimate.

Phil


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