Recently, many kinds of real-time applications have become available over IP networks. It is important to measure network performance for such applications before making use of real applications. The authors developed a general purpose traffic measurement tool for IP networks. This system can generate any kind of traffic flexibly and calculate network performance such as throughput, delay and loss rate according to the packers to be observed. In this paper, the concept and implementation of this tool are described in detail. As an example of network measurements, we also conducted subjective assessment tests for Internet telephony and demonstrated the validity of this tool.

An ATM (asynchronous transfer mode) network architecture for supporting connectionless service aimed at inter-LAN communication and high-performance distributed applications is presented. Two service scenarios, the related reference configuration, and a possible internetwork scenario for supporting the connectionless mode terminal are presented. A discussion is also presented of addressing and routing schemes and the two types of cell transport methods proposed for interconnection between the customer premises network and the connectionless service function (CLSF) located within the ATM network. The appropriate solutions for the cell transport methods are shown. As an application of the ATM connectionless service, a description is given of the gateway architecture supporting the inter-LAN communication via the CLSF.>