Competition for network resources becomes serios in modern data networks with any kind of connectivity. This is true both among applications and users within each site and among sites. As a result, the challenge of providing critical application performance guarantees is growing and growing.
■ Quality of Service (QoS) Provisioning
In the field of computer networking and other packet—switched telecommunication networks, the quality of service (QoS) refers to resource control mechanisms of reservation and enforcement. QoS is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. Especially, QoS guarantees come into play if the network capacity is insufficient, especially for real-time streaming multimedia applications such as VoIP, interactive games, IPTV, and video conferencing since these often require fixed bit rate and are delay sensitive.
■ Network Calculus and its Application
Network calculus is a theoretical framework for analyzing performance guarantees in computer networks. As traffic flows through network, it is subject to constraints imposed by the system components, for example link capacity, leaky buckets-base rate limiter, congestion control, and background traffic. The results derived in the network calculus theory enable one to understand fundamental properties of such flows and systems, and hence better deploy flow control, multimedia smoothing, delay control, and integrated service provisioning in computer networks.