By default, when there are multiple equal-cost paths to the same destination for the active route, the JUNOS software uses a hash algorithm to choose one of the next-hop addresses to install into the forwarding table. Whenever the set of next hops for a destination changes in any way, the next-hop address is rechosen, also at using the hash algorithm.
You can configure the JUNOS software so that, for the active route, all next-hop addresses for a destination are installed in the forwarding table. This feature is called per-packet load balancing. You can use load balancing to spread traffic across multiple paths between routers. The behavior of the load-balance per-packet function depends on the version of the Internet Processor application-specific integrated circuit (ASIC) in your routing platform. In this scenario, we perform load balancing for all routes and for a limited set of routes
Complete configuration scenario - see attached
Annotate your configuration with comments where needed. - see attached