Date Added: Jan 2010
The focus of this paper is on the QoS routing algorithms and protocols for unicast and multicast in the IPv4 based Internet that constrains or optimizes an individual or combination of metrics. The desired features of a router supporting QoS have been discussed in detail. QoS routing leads to an increase in computation more complex path selection process and communication protocol overhead due to increase in state information. However, the increase in cost is counterbalanced by the increase in performance. A study of work related to the cost/performance tradeoff of QoS routing is presented. Being an area of active research, QoS routing has a number of open issues that has been discussed as part of this paper.