On Thu, Oct 21, 2010 at 12:42 AM, qiu ying <[email protected]> wrote:
> Hi,all
> I found mote(ctp+4bitle) sometimes failed to send ctp packet as no
> parent is chosen, even the root is very close the mote.
> The reason I found is VERY_LARGE_ETX_VALUE is set to 0xffff in
> tos/lib/net/4bitle/LinkEstimatorP.nc,  it is too large maybe, once
> used in computeETX(), the etx is much larger than ETX_THRESHOLD for a
> long time due to the EWMA algorithm.  SVN r4975 make this
> change(0xff-> 0xffff), anyone know the reason?

We wanted the largest 16-bit value we could return to indicate an
invalid ETX. Setting this constant to 0xFF can confuse exceptionally
large ETX (e.g., ETX=25) as an invalid ETX.

I would need a little bit more information to help you debug CTP. How
can I reproduce this bug?

- om_p

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