Latency Evaluation of WDM-Based Packet/Path Integrated Networks

Wavelength Division Multiplexing (WDM) technology multiplexes optical signals that take different wavelengths into the optical fiber, and offers a high bandwidth transmission. As an application of the WDM technology to the Internet, several network architectures have been discussed; packet-based architecture such as IP over WDM and path-based architecture that establishes a lightpath between nodes on-demand basis. In this paper, we consider a packet/path integration for WDM-based optical networks. The main advantage of the packet/path integration is to enjoy strengths of both packet switching paradigm and circuit switching paradigm. We evaluate the performance of packet/path integrated network via computer simulations with respect to the latency, which is defined from when a data transfer request arises to when the data transfer completes. We first show that the latency much depends on the amount of wavelength resources allocated to the packet switched network. We therefore develop a wavelength allocation algorithm that determines the amount of wavelength resources based on the queue length of buffers in packet switched network. Computer simulations show that our algorithm lowers the latency of the packet/path integrated network even when the arrival rate of data transfer requests drastically changes.