In order to increase the flexibility and the extensibility for packet transmission, the active network approach, that makes network nodes programmable, is very promising. Every packet includes a program specifying behavior of the packet at network nodes, and the network nodes only have the functions to execute programs of the packet. In an active network, network congestion management is achieved more flexibly and intelligently than that in the conventional internet. A number of mechanisms for congestion management are easily developed because various network functions such as QoS routing and congestion detection are easily combined in the same network nodes. By executing different routing protocols that use different levels of the link information, a congestion management scheme can be customized by users. This paper shows how QoS routing and congestion detection achieve a congestion management over an active internetwork system.

This paper first proposes an object-oriented service network model, which is composed of application, server and resource object groups, from both viewpoints of rapid and smooth introduction and effective execution of the next generation IN services. The paper also, proposes a testbed system, which is referred to as "To-be-IN (Testbed on Object-oriented and B-ISDN Environment for IN)", for evaluating network architecture based on the proposed model. Using the testbed, several technical issues can be solved such as object-oriented realization of IN services, a provision of distribution transparent environment and a transition strategy from today's IN network. The testbed system is constructed on a currently available computing environment in which a distribution transparency mechanism is added. This system provides Service Creation Environment (SCE) for a purpose of achieving seamless software transfer from a development phase to an operation phase in the object-oriented service network model. The paper finally summarizes some results of an experimental implementation of the system.