If the total IGP cost to a destination are same for two path, these paths are called Equal Cost Multi Path. Normally if there are two path that have same IGP cost, in Alcatel-Lucent Service Routers, lower interface wins and the traffic goes through it.
Traffic Flow Without ECMP
Think about the above topology, without ECMP the traffic only goes through the A path. And when you use the below commands to see the tables, you will realize the below results: