IP traffic grooming over WDM optical networks

Abstract

IP over WDM has emerged as a winning network architecture to facilitate today's IP centric Internet. Although the total amount of bandwidth demands keeps increasing, there still exists a huge gap between the increasing full-wavelength capacity and the existing low-rate IP traffic. Efficiently grooming low-rate traffic stream to high-capacity lightpaths helps to alleviate the bandwidth mismatch, effectively improve the network resource utilization, and reduce the overall network cost. In this paper, we study traffic grooming problem in IP over WDM framework. The problem of minimizing the total number of transmitters and receivers in the networks is formulated as an integer linear programming (ILP) optimization problem. The ILP formulation produces optimal solutions for static traffic demands. However, applying the ILP solution to large and realistic networks is not practical due to its prohibitively large computation time. We therefore develop a heuristic algorithm, namely traffic aggregation algorithm. A significant improvement on wavelength utilization is observed in our experiments when we use our traffic aggregation algorithm. I. INTRODUCTION The popularity of the Internet and Internet protocol (IP)- based Intranet is promising enormous growth in data traffic originating from hosts that are IP endpoints. This growth is being fueled by various applications such as those driven by World-Wide-Web (WWW) and by the indirect impact of increased computing power and storage capacity at the end systems. The advent of new services with increasing intelligence and the corresponding bandwidth demands are further adding to the traffic growth. New access technologies such as Asymmetric Digital Subscriber Line (ADSL), High- bit-rate Digital Subscriber Line (HDSL), and fiber to the home (FTTH) would remove the access bottlenecks and enforce an even faster growth of demand on the backbone network. These changing trends have led to a fundamental shift in traffic patterns and the traffic is mostly due to data communications. In the past, the amount of data traffic on carrier networks was smaller than the voice-centric traffic. Therefore, the carrier networks were designed to primarily support voice traffic, and the data traffic was transmitted using the voice channels. Now, the core networks are being designed primarily for data traffic with voice support at the edges. The voice can be carried in the core networks using voice-over-IP or similar paradigms. To meet these growing demands, WDM will continue to emerge as a dominating trend for use in backbone networks. The research reported in this paper is funded in part by the National Science Foundation under grant ANI-0087746, grant ANI-0434872 and grant ANI- 0323374. Architectures will include to satisfy the need for better quality of service (QoS), protection, and availability guarantees in IP networks. WDM significantly increases the fiber capacity utilization by dividing the available bandwidth into non-overlapping wavelength channels, supporting connections between the two end nodes by establishing an all-optical channel, namely lightpath, which allows use of different formats, bit-rates, and protocol transparency. At the same time, most network designers believe that IP is going to be the common traffic convergence layer in communication networks. Consequently, IP over WDM has been envisioned as the winning combination of the network architecture.