Techniques are described for extending a two-way active measurement protocol (TWAMP) to enable measurement of service key performance indicators (KPIs) in a software defined network (SDN) and network function virtualization (NFV) architecture. The TWAMP extensions enable control messaging to be handled by a TWAMP control client executed on a centralized controller, and data messaging to be handled by a TWAMP session initiator executed on a separate network device. Techniques are also described for extending TWAMP to enable measurement of any of a plurality of service KPIs for a given service supported at a TWAMP server. The service KPIs may include one or more of keepalive measurements, round trip time measurements, path delay measurements, service latency measurements, or service load measurements. The TWAMP extensions for the service KPIs may be used in both conventional network architectures and in SDN and NFV architectures.