> I would need a little bit more information to help you debug CTP. How
> can I reproduce this bug?
It's easy to reproduce it on my platform(atmega1281+rf230). Use 2 mote
with TestNetwork application, suppose root id is 0, the other is 1.
Start the root first, then start mote 1, the etx changes as follows:
(I add a printf in updateETX(), LinkEstimatorP.nc)
etx=6553
etx=5906
etx=5320
etx=4791
etx=4314
etx=3885
etx=3498
etx=3150
etx=2836
etx=2554
etx=2300
etx=2071
etx=1865
etx=1679
etx=1512
etx=1362
...

but in the reverse power on order(start mote1 then start root), it's OK.
etx=10
etx=14
etx=13
etx=15
etx=14
...

2010/10/22 Omprakash Gnawali <[email protected]>:
> 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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