1 Quality-of-Service Mechanisms in IP-over-WDM Networks

Classical approaches to quality-of-service (QoS) provisioning in IP networks are difficult to apply in all-optical networks. This is mainly because there is no optical counterpart to the store-and-forward model that mandates the use of buffers for queuing packets during contention for bandwidth in electronic packet switches. Since plain IP assumes a best effort service model, there is a need to devise mechanisms for QoS provisioning in IP over wavelength-division-multiplexing, or IP-over-WDM, networks. Such mechanisms must consider the physical characteristics and limitations of the optical domain. This paper presents a classification and a survey of recent proposals for QoS provisioning and enforcement in IP-over-WDM networks. The different QoS proposals surveyed cover three major optical switching methods: wavelength routing, optical packet switching and optical burst switching. 1