The value of vRtrInetAllCidrRouteBkupMetric indicates the routing
metric for a backup route. The semantics of this metric are determined
by the routing-protocol specified in the route's ipCidrRouteProto
value. The value of vRtrInetAllCidrRouteBkupMetric is only
valid when vRtrInetAllCidrRouteBkupFlags has a value of 'hasLfa'.