Towards a new Internet architecture
Based on the IP best-effort paradigm, the Internet has evolved from a research network to an everyday commodity. Still, some critical issues, some identified a decade ago, have not yet been solved satisfactorily. We find ourselves at a crossroad, where the deployment of and the prospects of QoS-aware technologies will shape the future evolution of the Internet, either as QoS-aware or over-provisioned. The IETF IntServ (integrated services) and DiffServ (differentiated services) models are two solutions offered to help to solve the QoS problem. Also, multi-protocol label switching (MPLS) has provided a powerful tool that supports traffic engineering in IP networks. At the infrastructure level, wavelength divisionmultiplexing (WDM) systems have vastly expanded transport capacity, another boost to QoS-sensitive applications on the Internet. Besides QoS awareness, the adaptation of the Internet to support mobility and security are additional key factors for the direction the Internet may take in future. This special issue focuses primarily on two of the three mentioned critical issues of the Internet––QoS awareness and mobility–– with a glimpse at important application issues. The invited paper on Grids and Research Networks by Kyriakos Baxevanidis et al. looks at a futuristic application and evaluates the challenges in sharing resources in a worldwide grid. Though initially driven by research requirements, a number of commercial applications loom ahead. The authors summarize requirements of an emerging class of advanced Grid applications, and then go on to discuss the technical and policy issues involved. The example used is the European R&D network G EANT. It turns out that there are many, partially conflicting requirements, for example on providing storage capacity, on QoS in the involved networks and on inter-working management systems. They propose granting usage by ‘‘management decision’’ instead of charging, which is considered too complex, but this is certainly one of the debatable issues that will occupy us for some time. All in all, the diverse Grid projects are certainly something to follow up on in the coming years. For users, the perceived quality of applications may depend on response times for the application. Wael Noureddine and Fouad Tobagi look at how to differentiate traffic in the network such that users get an appropriate response depending on the type of application used. They distinguish between highly interactive services, such as Telnet, interactive services, such as Web applications, and non-interactive services. Using DiffServ and assured forwarding, they simulate the optimisation of traffic by two different methods. In one approach, they optimise by marking packets based on the application, giving highest priority to Telnet-type services, less priority to Web-type services and least to others. In the second approach, they differentiate according to TCP state. Their results show that both approaches improve the perceived quality of the applications, with a small advantage for the TCP-state based approach, which penalises other applications less. Yu-Ben Miao, Wen-Shyang Hwang and CeKuen Shieh propose a method to make existing applications QoS-aware instead of redesigning them from scratch. They use a module called RLR (RSVP Library Redirection), which intercepts socket routine calls so that, with appropriate Computer Networks 40 (2002) 1–4