Hello,
I extracted the output of sniffer (.psd file) to an excell file in order to analyse number of re-transmitted packets, lost packets and damaged packets based on NESN and SN info. To make the algorithm, I need to understand what happened in the following cases. I would appreciate If you contribute to this post with your ideas.
Connection Interval=75 milliseconds, Latency=0;
1- Packet No: 237
After packet 236, during the next connection event we can’t see any packet sent (+150 milisec.). Do you think that the packet from master is lost or no packets have been sent at all? Since latency is 0, in each connection event there is supposed to be a packet from Master. In which cases no packets are sent although latency=0?
2-Packet No: 239
There is no response from slave to the master in the connection event. Since the sniffer is located very close to the slave, I dont think the packet is lost. Maybe the buffer of
slave was full. Why do you think that the slave did not send the response in that connection event but in the next one?
3- Packet No: 247
Normally the connection events always start with a packet from Master. Why in this connection event only slave sends the data although it did not recieve anything from Master? If you notice, the slave sends the same SN and NESN with its last packet and in the next connection event, master does not increase its NESN at 248 but at 250 although it recieves the same packets from slave.
4- Packet No: 252 -255
Like in 236, during 3 connection events slave does not send any packets although the Master keeps asking. Why do you think this happened? Is this situation counted as a kind of error?
5- Packet No: 258
There is FCS error on the packet 258 that belongs to master. However, the next MASTER packet 260 increased its NESN. Does that mean, if the CRC is not ok and thus the packet has an error, in the next re-transmission of the same packet NESN should be increased anyway? Well, it seems so.
6- Packet No: 263
NESN of the master is 1; but the SN of the slave is 0. There should be an error. But this error is not an FCS error neither is a packet lost. So when I count the nr of errors, should I also add this? Because packet 265 is obviously a retransmission of 263.
7- Packet No: 311
Same as the first question, what would be a reason for 3 connection events there is no packet exchange although the latency is 0?