1. A method comprising: receiving a first Internet protocol (IP) flow for an IP session for a subscriber; acquiring a service policy for the subscriber from a Policy and Charging Rules Function (PCRF), wherein the service policy identifies one or more service function chain types that can be associated with one or more IP flows for the subscriber; selecting a first service function group from a plurality of service function groups to perform one or more services for the IP session for the subscriber, wherein each of the plurality of service function groups comprises a plurality of service function chain types and wherein each service function chain type comprises an ordered combination of one or more service functions; assigning the IP session for the subscriber to the first service function group; and forwarding the first IP flow for the IP session of the subscriber across a first service function chain type for the first service function group based, at least in part, on the service policy for the subscriber.