Method to use IGP ECMP routing information for an IBGP peering.
route-balance method distributes a set of destination networks
that share the same IBGP Next Hop among available ECMP routes.
Each IBGP network has one route submitted to IP RTM.
traffic-balance uses all avaiable IGP ECMP routes. Each IBGP
network submitted to IP RTM number of times equal to number
IGP ECMP routes to IBGP Next Hop.