[Tinyos-help] Cycle detection in multihoplqi (surge) for tinyos-1.x

[Philip Levis]

On Sep 10, 2007, at 5:40 AM, Paolo Masci wrote:

> Hi,
>
> I was giving a look to the multihop routing
> algorithm implemented in tos/lib/MultiHopLQI.
> I have noticed that nodes select their parent
> evaluating the end-to-end link quality
> of the path to the base station.
>
> In order to avoid cycles, shouldn't they select
> their parent evaluating also the distance from
> the base station? Without the check on the distance,
> there is no guarantee that the packet gets closer
> to the base station: isn't there the risk of cycles?
> (for example, I guess it may happen in scenarios
> with long paths and with link quality that frequently
> changes)

No. It expects route cost to monotonically decrease. Take a look at  
the logic which checks if a received packet is from a node with a  
lower cost. That implies there might be a cycle.

Phil