Supporting multiple classes of services in IP over WDM networks

In this paper, we consider the next generation Optical Internet, where direct communication channels between IP entities are provided through an all-optical WDM layer. Since current IP provides only best effort service, supporting Quality of Service (QoS) has become a crucial issue. We propose a simple, yet efficient priority scheme to support basic QoS at the WDM layer of the Optical Internet. Unlike existing approaches that depend on buffers (queues) and scheduling algorithms (e.g., Fair Queuing), our scheme does not mandate any buffer in the WDM layer in order to differentiate the services. The proposed scheme is based on the concept of using an offset time between a control (set-up) packet and the corresponding data burst as in optical burnt switching (OBS). More specifically, by assigning different offset times to different classes, it is possible for a higher priority class to be isolated from lower priority classes. We quantify the offset time required for class isolation, and analyze the blocking probability of each class.