Traffic Management in IP Networks

Louisiana State University, Baton Rouge LA

Investigators

Abstract

There is an immense demand for quality of service (QoS) in the Internet. One key element of quality of service is traffic management. Since the network traffic is bursty, it is difficult to make any QoS guarantees without proper control of traffic. Currently, Internet Protocol (IP) has only minimal traffic management capabilities. The packets are dropped when the queue exceeds the buffer capacity. The transmission control protocol (TCP) uses the packet drop as a signal of congestion and reduces its load. While in the past, this strategy has worked satisfactorily, there is need for better strategies for two reasons. First, a large part of the traffic, particularly, voice and video traffic does not use TCP. Continuous media traffic uses User Datagram Protocol (UDP). The proportion of UDP traffic is increasing at a faster pace than TCP traffic. The UDP traffic is congestion insensitive in the sense that UDP sources do not reduce their load in response to congestion. Second, the bandwidth of the networks as well as the distances are increasing. For very high distance-bandwidth product networks, packet drop is not the optimal congestion indication. Several megabytes of data may be lost in the time required to detect and respond to packet losses. Therefore, a better strategy for traffic management in IP networks is required. Recognizing the need for direct feedback of congestion information, the Internet Engineering Task Force (IETF) has come up with an Explicit Congestion Notification (ECN) method for IP routers. A bit in the IP header is set when the routers are congested. ECN is much more powerful than the simple packet drop indication used by existing routers and is suitable for high distance-bandwidth networks. Unfortunately, to realize the full potential of ECN, several questions need to be answered. In this research proposal, the PIs propose a comprehensive program of research on traffic management in IP networks. They propose to develop a new set of traffic management algorithms for IP networks based on Explicit Congestion Notification mechanism. A total of 18 different issues will be analyzed. The PIs have identified potential solutions and approaches for each of these issues. Specifically, they propose to work on a new congestion detection and buffer management scheme for routers, a mechanism for TCP to react to ECN messages from the network. One of the important goals of this research is to make TCP traffic management algorithm free of any bias based on round trip time and number of congested gateways traveled. The proposed research will be based on theoretical analysis and simulations. The PI's approach will be a formal analysis of simple scenarios, heuristic analysis of more complex scenarios and validation using simulations. The emphasis will be to develop simple solutions. However, the performance lost in exchange of simplicity will be theoretically analyzed. Traffic management is the key in providing QoS. Currently, a significant amount of NSF, DARPA, and other research funding as well as energy in networking is being spent on QoS issues. When QoS based solutions (integrated services, differentiated services, or multiprotocol label switching) are deployed, the need for traffic management will become apparent and the PIs expect to see an immediate need for proper methods for traffic management. This proposal is, therefore, timely and important.