Abstract

Large Internet Service Providers (ISPs) are in the process of upgrading their links from lower rates, (e.g., 45 Mb/s to 620 Mb/s) to above 2.5 Gb/s. The lower speed links are characteristically routed over Digital Cross-connect Systems (DCSs) and/ or SONET OC-48/OC-192 (SDH STM 16/64) rings. However, almost all the higher speed links that have been installed today are routed directly onto Wavelength-Division Multiplexing (WDM) systems. Optical Cross-connects (OXCs) are now becoming available on the market, some with photonic fabrics and some with electronic fabrics. This OXC layer, along with distributed sig-naling and routing capabilities, can establish connections quickly and on-demand. This ability, coupled with a signaling mechanism between the routers and OXCs, such as the User Network Interface (UNI),¹ establishes the foundation for a rapidly “reconfigurable” topology for the IP layer.² While most managers of large ISP networks agree that at some point in time the volume of high-speed links that needs to be provisioned will mandate their deployment over an OXC layer, they are also keenly concerned about containing costs. Consequently, they are looking for other concrete advantages to accelerate this deployment, as well as justify the need for such a dynamically reconfigurable topology.

© 2002 Optical Society of America