Hi Erik,
thank you for your reviews and for sharing thoughts on the selection of the destination IPv6 address. Following recommendations from Adam, I've updated the document to use the proper representation of IPv6 addresses and refer to them as "IPv4-mapped IPv4 loopback addresses". These updates are in the attached diff.. Adam also noted that RFC 8504 doesn't have a similar wording regarding the handling of packets addressed to an address from 127/8 network as RFC 1812 (of course, referring to IPv4-mapped 127/8 addresses):
A router SHOULD NOT forward, except over a loopback interface, any
packet that has a destination address on network 127. A router
MAY have a switch that allows the network manager to disable these
checks. If such a switch is provided, it MUST default to
performing the checks.
I'd note, that the egress BFD system is expected to accept a BFD packet with the destination IP address from the specified range without being provisioned for the specific address from that range. Perhaps that makes the use of this range possible even though its special handling is not explicitly documented.
Best regards,
Greg