Dear Victor,
You are right in saying that in the ND protocol, PC1 would send an NS packet, and PC4 would respond with an NA packet. Also, if you examine the wireshark capture, you will see these two packets are captured at first.
However, as stated in the question feedback part, you should wait enough time and check all NS and NA packets captured by wireshark. Later on, you will see new NS and NA packets, which are in the direction stated in the options (PC4 sends NS, PC1 sends NA). This seems counter intuitive as you already explained. But these NS and NA packets are not part of the initial ND protocol. These packets are used to verify that the neighbor is still reachable. The conclusion is that NS and NA packets can be used for other purposes.
In short, NS and NA packets are sent in both directions, and you are expected to observe the unexpected direction.
Hope this answers your question. Feel free to ask for any clarifications here on the forum or send me an email (edin.guso@epfl.ch).
Best,
Edin
You are right in saying that in the ND protocol, PC1 would send an NS packet, and PC4 would respond with an NA packet. Also, if you examine the wireshark capture, you will see these two packets are captured at first.
However, as stated in the question feedback part, you should wait enough time and check all NS and NA packets captured by wireshark. Later on, you will see new NS and NA packets, which are in the direction stated in the options (PC4 sends NS, PC1 sends NA). This seems counter intuitive as you already explained. But these NS and NA packets are not part of the initial ND protocol. These packets are used to verify that the neighbor is still reachable. The conclusion is that NS and NA packets can be used for other purposes.
In short, NS and NA packets are sent in both directions, and you are expected to observe the unexpected direction.
Hope this answers your question. Feel free to ask for any clarifications here on the forum or send me an email (edin.guso@epfl.ch).
Best,
Edin
