vRtrLdpIfIndex is an index for the row entry and is used
mutually exclusively with the vRtrLdpPeerAddress field. If
the vRtrLdpPeerAddress field is 0.0.0.0, then vRtrLdpIfIndex
is the index for the interface on the virtual router and
must be non-zero. Otherwise, vRtrLdpPeerAddress refers to
a targeted peer and its vRtrLdpIfIndex is 0.