IMPLEMENTATION OF OPTICAL BURST SWITCHING FRAMEWORK IN PTOLEMY SIMULATOR Shakeel Ahmad * , Sireen Malik ** Department of Communication Networks Hamburg University of Technology, Germany Email:{shakeel.ahmad, s.malik}@tu-harburg.de Abstract We present an architecture for Optical Burst Switching (OBS) node and the implementation of OBS for a discrete event simulator like Ptolemy. This implementation allows to do performance analysis of OBS. Currently we implemented Just-In-Time (JIT) reservation scheme. However the software implementation provides flexibility to use other reservation schemes. Keywords: Optical burst switching, OBS, Implementation of OBS in Ptolemy simulator, Just-In-Time, JIT. 1. INTRODUCTION The number of internet users and the variety of applications demanding more and more bandwidth keeps on increasing day by day. These ever-increasing demands need ever-increasing bandwidth. Here optical communication comes into the picture. It provides huge amount of bandwidth and leads to the popular concept of optical Internet. The potential of optical fiber was realized fully when wavelength division multiplexing (WDM) was invented. It was determined that with wavelengths and values typically used in optical networks today it is theoretically possible to transmit data rates of up to 100 terabit per second. But because of the absence of stable optical buffer and optical logic at each of the intermediate nodes optical-electronic-optical (OEO) conversion is required. Presently there is a great mismatch between the electronic processing speed and optical transmission speeds which creates a bottleneck. To avoid OEO conversion, researchers proposed All- Optical-Networks (AON) [1] where user’s data would travel completely in optical domain. With regard to AONs, Optical-Packet-Switched-Networks (OPSNs) seems to be the most suitable candidate for future optical network. However in view of the present technological limitations Optical Burst Switching (OBS) is the most suitable AON control framework. It combines the best feature of both circuit switching and packet switching [2]. Figure 1: Node and network architecture for OBS Figure 1 shows a general diagram for node and architecture of OBS. At the edge node upper layer user data is collected and aggregated into fixed/variable (depending upon aggregation algorithm) sized units called bursts. Once a burst is ready edge node creates bust header control (BHC) and sends it into the network on dedicated control channel. The purpose of sending the BHC is to establish an optical path so that the following burst could pass through with out buffering. At each of the intermediate nodes BHC is converted back to electronic domain, information is extracted from it and if reservation can be made then this BHC is forwarded to the next node. Edge node then transmits the burst after an offset time without knowing that whether a complete path has been established or not. This is known as one-way- reservation. Due to one-way-reservation OBS suffers from high burst drop rate. Predicting the effects of different OBS parameters like offset time, Maximum Burst Assembly Time (MaxBAT), Maximum Burst Length (MaxBL), number of wavelengths w and *This paper is based on the student project of Mr. Shakeel Ahmad as part of his M.Sc. at TUHH. **Mr. Sireen Malik is a Ph.D. candidate under supervision of Prof. Dr. Ulrich Killat, working on the MultiTeraNet project funded by the ministry of education and research, Germany.