Dear all (Eric, Thomas, Wasif, Srikanth), thanks for your input (I was on vacation so here comes my late reply).
> you need a sniffer > > trying to do this by getting somekind of tell tale from the code is very > difficult. > > you need to instrument the network. Yes, but that's really what I wanted to avoid. ;-) I have already used a sniffing node that never saw the duplicate (software) ACK (though it didn't see some other packets either). While this supports the idea of the receiving node pulling out an old packet from somewhere, it's not really sure. I'll try to use the CC2420x driver first and see what happens. If the problem remains, I might have to use some instrumentation. > On Fri, Aug 30, 2013 at 10:10 AM, Christian Renner > <[email protected] <mailto:[email protected]>> wrote: > > > > We have 3 nodes: one receiver R and two senders A and B. Software > ACKs > > are used. > > Have you tried with hardware ACK? Is there a reason you're using > software ACKs? The ACKs carry additional information, so that I cannot go with hardware acks. > > > > - I installed a sniffing node to see what really is on the > channel: only > > the ACK from R to A (no ACK from R to B!) > > Just out of curiosity - what sniffer are you using? I used a cc2531emk > [1] and I know it missed some packets either because of radio > interference/losses (which makes sense) or potentially due to USB > issues (which doesn't, and can be very misleading). Well, I just went along with the normal TinyOS base station (which just gives low support really for debugging, I know). I haven't tried anything else yet. > > The question now is if it is possible that a packet from the > RXFIFO is > > obtained a second time and how this issue could be solved. > > Perhaps someone more knowledgeable than me should comment on this, but > my understanding is that this is very unlikely because of the nature > of the design. I believe the FIFO is emptied as it is read. That's what I thought, too. As stated above, I'll try the suggestion by Thomas Schmid (CC2420x driver) and will decide what to do if that fails. Best Christian _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
