Delay performance analysis of the new Internet services with guaranteed QoS

In addition to the traditional best effort Internet protocol (IP) service of the Internet, the Internet Engineering Task Force has defined two new services that provide quality of service guarantees on throughput and delay. In this paper, we analyze the delay performance that can be achieved with the service that provides the most firm guarantees-the guaranteed quality of service. Using a voice and a video application as examples, the end-to-end delay is calculated. Three different scenarios are presented: local, regional, and long distance, differing in the distance covered and the number of IP routers traversed. It is shown that even in the long-distance case, the achievable end-to-end delay for the guaranteed service can be kept sufficiently low to support interactive applications with strict delay requirements. It is concluded that for low-rate applications, the efficiency cannot be higher than about 60-75%. For connections traversing a large number of routers, the variable delay as advertised by the routers is much higher than the expected delay. The second new service, called the controlled-load network element service, provides less firm delay guarantees. The end-to-end delay for this service is estimated using similar techniques. The results suggest that this service is suitable for interactive applications in the local and regional scenarios only. For the long distance scenario, the end-to-end delay is expected to be below 300 ms.