Not all OSes, Windows being a notable example, support using the interface name as the zone id of IPv6 link local unicast and multicast addresses. However, they all support using the interface index.
Thus, in order to ensure proper behavior on all supported OSes, this modifies the address normalization logic for interface names to append the interfaces index as the IPv6 zone for link local unicast and multicast addresses instead of the passed address.
Not all OSes, Windows being a notable example, support using the interface name as the zone id of IPv6 link local unicast and multicast addresses. However, they all support using the interface index.
Thus, in order to ensure proper behavior on all supported OSes, this modifies the address normalization logic for interface names to append the interfaces index as the IPv6 zone for link local unicast and multicast addresses instead of the passed address.