The early RFCs were written more informally, so it's hard to say what was optional. However, the consensus was that SLAAC was supposed to be the main way to con

The early RFCs were written more informally, so it's hard to say what was optional. However, the consensus was that SLAAC was supposed to be the main way to configure IPv6, along with fully manual configuration. > In protocol design its common to leverage identifiers from lower layers for addressing. Yes, that's why my email has the IP address of the mail server. And why my WhatsUp contains the IMEI of my phone.