Managing service-level agreements in metro ethernet networks using backpressure

Ethernet, which has long been used for local area networks (LANs), is increasingly being employed for metropolitan area networks (MANs). Because it is familiar, simple, and cost-effective, it is becoming popular as a means of transporting data in a MAN. A prerequisite for providing different levels of service in a MAN is the ability to support and maintain service-level agreements (SLAs). Proper management of SLAs ensures that users do not violate their contracts and makes it possible to guarantee quality of service (QoS). Such management requires support for traffic flow control, monitoring, and policing. This paper presents a novel Ethernet traffic-policing mechanism based on backpressure and able to provide feedback to an end user or access network when SLAs are violated, instead of simply dropping packets. The performance of this mechanism is analyzed by means of tests. The tests focus on the effects of the mechanism on throughput and fairness for transmission control protocol (TCP) traffic and on jitter and packet drops for user datagram protocol (UDP) multimedia traffic. (C) 2003 Lucent Technologies Inc.