On the Departure Process of Burst Aggregation Algorithms in Optical Burst Switching Xenia Mountrouidou 1 and Harry Perros 2 IBM 1 , 4205 S. Miami Blvd. Durham, NC 27703, USA Computer Science Department 2 , North Carolina State University, Raleigh, NC 27695, USA Abstract We characterize analytically the departure process from the following three burst ag- gregation algorithms: the time based aggregation algorithm, the burst-length based aggregation algorithm and the time and burst-length based aggregation algorithm. The arrival process of packets is assumed to be Poisson or bursty modeled by an Interrupted Poisson Process (IPP). The analytic results are approximate and vali- dation against simulation data showed that they have good accuracy. 1 Introduction An important design aspect of an Optical Burst Switched (OBS) network is the burst aggregation process performed at the edge nodes. This process concentrates upper layer packets which are then transmitted optically over the OBS network. In view of this, the burst aggregation strategy defines the burst arrival process to the OBS network. The burst arrival process depends on the parameters of the burst aggregation process, and so far it has not been adequately studied. In the majority of OBS related studies it is assumed that burst arrivals are similar to a packet arrival. The Poisson assumption has been used extensively to represent the burst arrival process. The results obtained in Email addresses: pmountr@us.ibm.com, hp@ncsu.edu (Xenia Mountrouidou 1 and Harry Perros 2 ). Preprint submitted to Elsevier 14 September 2008