In very simple words MT topology enables FIB (Forwarding Information Base) virtualization. By enabling more than topology, we have a separate RIB/FIB per topology.
Think of it like FBF (Filter Based forwarind or PBR) on steroids. As it also supports routing protocols (OSPF, BGP) along with static routing of course, we also get the benefits of dynamic routing.
Finally in order to place traffic into the desired topology ingress to each router you can do it either with Firewall Filter or based on interface.
