In recent years many multimedia services, such as voice over IP and videoconferencing, have been developed and applied popularly over the Internet. These multimedia services become key applications in home networks, but the bandwidth requirements for these multimedia services grow up rapidly. Thus how to provide a certain degree of Quality of Services (QoS) for the multimedia applications in edge routers is an important issue. The framework of differentiated services (DiffServ) is able to provide QoS by means of packet classifications, flow aggregation and scheduling mechanisms. In the paper a DiffServ edge router is implemented on the Intel IXP425 network processor platform. Network processors are emerging as a programmable alternative to the traditional ASIC-based solutions in scaling up the user-plane processing of network services. The performance of the implemented DiffServ edge router is evaluated by experiments. Exprimental results demonstrate the validation of the implemented system.