4.5 IP Network Issues

The evolution towards a common, flexible, and seamless IP-based core network that will connect heterogeneous networks gives rise to several issues at the network layer [91 160]. The need for ensured QoS is the key of this evolution. Fundamentally, the day that packet-switched networks can credibly approach the QoS of circuit-switched networks is the day customers stop paying for two networks. The QoS problem involves integrating delay-sensitive applications such as voice, audio, and video onto a single network with delay-insensitive applications, such as e-mail, fax, and static file transfer. That network must be able to discriminate, differentiate, and deliver communications, content, and commerce services. Moreover, it needs to support communication services creation, modification, bundling, and billing in a way that is unobtrusive yet powerful for end users, especially business users. The scenario becomes more challenging as QoS and security issues are faced in a mobile environment. The Internet has not been designed with mobility in mind and lacks mechanisms to support mobile users. Some architectures have been proposed for supporting mobility in the Internet. The most important is Mobile IP, which will be discussed in Section 4.5.2. Before that, some guidelines behind mobility management are discussed in Section 4.5.1. Proposals to solve some of the open issues in Mobile IP are described in Section 4.5.3.