Hi Ghaith,
We need “something” that wants to send some data. This could be a ping like I did or an application that wants to reach some server. In my example, I sent a ping to FE80::C002:3FF:FEE4:0.
The solicited node multicast group address starts with FF02::1:FF /104. We take this address and the last 6 hexadecimal characters of the address I’m trying to reach, our complete address will be ff02::1:ffe4:0 (you can see this in the wireshark capture).
R2 is the only device that will be listening to this multicast group address. It will receive the neighbor solicitation from R1 and will respond to it.
Rene