High Performance and Network Processors -- Challenges in Implementing an ESP Service -- The Role of Network Processors in Active Networks -- Towards High-Performance Active Networking -- Application of Hardware Accelerated Extensible Network Nodes for Internet Worm and Virus Protection -- High-Level Active Network Applications -- Active Routing and Forwarding in Active IP Networks -- A Sustainable Framework for Multimedia Data Streaming -- Deployment of Collaborative Web Caching with Active Networks -- Low-Level Active Network Applications -- A Retransmission Control Algorithm for Low-Latency UDP Stream on StreamCode-Base Active Networks -- TCP Enhancement Using Active Network Based Proxy Transport Service -- DataRouter: A Network-Layer Service for Application-Layer Forwarding -- Self-Organization of Active Services -- SORD: Self-Organizing Resource Discovery Protocol for ALAN -- Self-Configuring Active Services for Programmable Networks -- A Dynamic Neighbourhood Discovery Protocol for Active Overlay Networks -- Experiences with Service Engineering for Active Networks -- Chameleon: Realizing Automatic Service Composition for Extensible Active Routers -- Multiple Language Family Support for Programmable Network Systems -- Dynamic Deployment and Configuration of Differentiated Services Using Active Networks -- A Globally-Applied Component Model for Programmable Networking -- Active Routers in Action: Evaluation of the LARA++ Active Router Architecture in a Real-Life Network -- Management in Active Networks -- A Proactive Management Framework in Active Clusters -- A Policy-Based Management Architecture for Flexible Service Deployment in Active Networks -- Adaptation Planning for Active Networks -- Selected Topics in Active Networks -- Risky Business: Motivations for Markets in Programmable Networks -- Context-Aware Handover Based on Active Network Technology -- Implementation of Adaptive Control for P2P Overlays.

This volume of the LNCS series contains the proceedings of the 5th Internat- nal Working Conference on Active Networks (IWAN 2003) held in the ancient cultural city of Kyoto, Japan. This year we received 73 submissions. The increasing number indicates that Active Networks continues to be an attractive ?eld of research. Through - reful reviewing and discussion, our program committee decided to fully accept 21 papers. Three papers were conditionally accepted, and were included after shepherding by members of the technical program committee. This volume thus includes these 24 papers which were presented at IWAN 2003. Additional papers were presented in a poster session at the conference. The best paper award went to Kenneth L. Calvert, James N. Gri?oen, - jati Imam, and Jiangbo Li (University of Kentucky) for “Challenges in Imp- menting an ESP Service,” which begins these proceedings and which began the papers in the High Performance & Network Processors session. Papers in these proceedings are organized into seven sessions: High-Level Active Network - plications, Low-Level Active Network Applications, Self-Organization of Active Services, Management in Active Networks, Experiences with Service Engin- ring for Active Networks, and Selected Topics in Active Networks, ranging from risk management to context-aware handover and peer-to-peer communications.