Upstream Router Detection for RPF (1) Problem

PIM uses a separate routing mechanism for Reverse Path Forwarding (RPF)
Typical case: just refer to the unicast routing table
The gateway for a destination must be one of PIM neighbors

An IPv6 PIM neighbor is identified as a link-local address.
-> a global address must not be in the unicast routing table.

This constraint is not necessarily satisfied in IPv6:
IPv6 allows a node to assign multiple addresses on each interface.
Global addresses can be in the routing table via BGP4+ or by hand.
Even multiple link-local addresses can be assigned on a single interface.
RPF and PIM do not work due to the mismaches.