Solved: IMPv6 multicast neighbor discovery message question

hfakoor222 · ‎06-16-2023

When sending out neighbor discovery messages in ipv6 to the multicast address, all routers, FF02::2, for example:

Is the message sent to all nodes for that multicast group, or is a specific multicast address derived from the ipv6 destination ip address to send to a specific node? Or are both possible depending on the situation?

If the message is sent to a specific multicast mac address, how does the sending device construct the destination mac address?

Harold Ritter · ‎06-17-2023

Hi @hfakoor222 ,

The quick answer is that it depends, which icmpv6 message you are referring to. Here are some examples.

- The router solicitation message (RS) is sent to the all routers multicast address (ff02::2).

- The router advertisement message (RA) is sent to the all nodes multicast address (ff02::1)

- The neighbor solicitation message (NS) is sent to the solicited node multicast address (ff02::1:ffxx:xxxx where xx:xxxx are the last 24 bits of the solicited neighbor address). The refresh NS message might be sent to the neig