Despite its potential significant bandwidth savings, major network providers do not yet support multicast within their networks. This is because of the lack of efficient and scalable multicast primitives that (i) support various routing requirements of ISPs such as traffic engineering and service chaining, where a packet needs to pass through an ordered set of network services before reaching the receivers, and (ii) forward packets of large numbers of concurrent multicast sessions. My main contribution is addressing the scalability challenges by managing, reducing or eliminating the required state to be maintained at network switches.