The area of quality-of-service (QoS) routing is concerned with selecting routing paths while meeting strict end-toend service requirements involving resource constraints, while achieving optimum throughput in the network. The usefulness of QoS routing is not new. QoS routing is quite popular in the telecommunications industry because of the increased demand for satisfying multiple customer demands and obtaining increased utilization of network resources, while satisfying the varied user requirements.
A network is said to support QoS (Guerin et al., 1997; Peterson & Davie, 2000), if it has the capability of treating different packets differently. QoS technology has enabled service providers to support different levels of service to different customers, thereby capacitating them with the option to provide better levels of paid services to some customers more than to others. For example, some groups of customers may be concerned with a service that guarantees packet delivery, even if that means paying a higher price for these services, others may just as well be satisfied with relatively less reliable data transfer by paying less for their subscribed services. Networks that transport multimedia traffic, that is, voice, data, and video need differential treatments of different packets—while voice traffic is highly sensitive to time delay and the orderly delivery of packets, data traffic is relatively less sensitive to these, and videoconferencing traffic requires a dedicated connection for a fixed amount of time for the real-time, orderly delivery of packets.
Typical QoS routing-based performance metrics are bandwidth, delay, and throughput. While some applications require bandwidth guarantees, some others mandate the satisfiability of strict end-to-end delays, and others still require a high throughput, or a combination of both of these criteria (Ma, 1998).
Key Terms in this Chapter
Multi-Protocol Label Switching: A popular protocol for traffic engineering operating in layer 3, in synchronization with the Internet protocol (IP).
Label Switched Path (LSP): The paths along which the labeled packets in MPLS networks are transmitted.
Algorithm: An algorithm is a set of clear steps that is used to define how a task or a set of tasks can be accomplished.
QoS Routing: QoS routing is concerned with selecting routing paths while meeting strict end-to-end service requirements involving resource constraints, while achieving optimum throughput in the network.
Label Switched Router (LSR): An LSR is a backbone router in the physical network topology that runs the existing layer 3 IP protocol.
Routing: The mechanism by which a path or a set of paths is selected to send information or commodities.
Traffic Engineering (TE): An engineering technique or techniques where information and goods can be efficiently transmitted or transported.