The value of vRtrMldIfGroupVer1HostTimer indicates the time remaining
until the local router will assume that there are no longer any
MLD version 1 members on the IP subnet attached to this interface.
Upon hearing any MLDv1 Membership Report, this value is reset to
the group membership timer. While this time remaining is non-zero,
the local router ignores any MLDv2 Leave messages for this
group that it receives on this interface.