Moin! I reviewed this document and I'm good with it. The only minor purely cosmetic note is that it took me some time to understand why you record the port for the IPv6 relay chain. According to a discussion I had with Bernie that is to be able to have the agent stateless. Maybe add that to the motivation why you store it in the packet at the end of section 4 (, to allow stateless operation in a relay chain) So long -Ralf