Towards optical core: demand and technology driven future WAN architecture

Summary form only given. Wide area networks of the past involved both protocol and topological hierarchies. In particular, protocol hierarchy involved IP over ATM over SDH, ATM over SDH, and wideband private lines over SDH. Topological hierarchy in wide area networks (as well as in access and metro networks) involved edge (region) and core (inter-region) for IP, ATM, and SDH. Sometimes an extra layer of hierarchy (super core) was added. This topological hierarchy provided traffic aggregation and statistical multiplexing. It also allowed the advantage of economy of size of particular switches and of the transport bandwidth. Finally, this hierarchy also allowed easier operations. A confluence of factors is causing changes in the above architecture and even more fundamental changes will be required in the future. In particular, the explosive growth in traffic volume and emergence of true multi-wavelength, multi-service, optical networks will make flatter service networks supported by an optical core network more economical in the future. While the optical core can have ring, mesh, or hybrid topology, mesh architecture with flexible restoration capability (selectable per wavelength) will become increasingly more desirable for long haul transport. In this talk, we discuss the factors driving this shift in network architecture, and provide quantification of the cost advantage of the new architecture for realistic, national scale networks. We also discuss the impact of the new architecture on the requirements for network elements providing the optical transport network (OTN) as well as those (IP/ATM switches, SDH cross connects, etc.) in the service networks. Finally, we also discuss the new management and control paradigms as well as the opportunities for new revenue generating services resulting from this new architecture