[Tinyos-help] [TinyOs 2.x] ACK Bug?

[Pratibha S]

I get it, thanks :)

On Sat, Jan 3, 2009 at 3:31 AM, Philip Levis <pal at cs.stanford.edu> wrote:

>
> On Jan 2, 2009, at 11:19 AM, Michael Schippling wrote:
>
> Hmm...interesting. Why would #2 happen? Message overrun?
>>
>
> The current (2.1.0) code flushes only when a node receives a packet whose
> length is longer than the FIFO (128 bytes). Older stacks would flush on
> additional error conditions.
>
>
>>
>> If it was only #1 it would seem that you would have at worst
>> a 1::2^16 chance of a falsely correct CRC and then an even
>> smaller chance of it being the type field that was corrupted.
>>
>
> You'd think so, but... I'm not 100% sure. There could be other things going
> on in the radio stack. *shrug* If I had a free day or two I might try to get
> the bottom of it. But since assuming an L2 ack implies an L3 delivery is a
> bad idea to start with, I made TOSSIM keep this in account.
>
>
>>
>> That said, the chance of missing a valid ACK is much greater
>> than getting a false one.
>>
>
> Yes. False positives are rare, but they happen.
>
> Phil
>
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