Simple optical fabrics for scalable Terabit packet switches

The design of fabrics for Terabit packet switches and routers needs to consider the limitations imposed by the electronic technology; in particular, more and more attention has to be paid to information density and to power consumption and dissipation, as well as to power supply and footprint requirements. These issues make more difficult to package a packet switch in one single rack of equipment; thus, optical links start being used to interconnect the line cards with the switching fabric. In this paper, we consider optical interconnection architectures that exploit wavelength agility at line cards to control switching decisions. The actual feasibility and physical layer scalability of this approach is analyzed by considering different optical fabric alternatives to interconnect the line cards. The main contribution of the paper is the characterization of these optical fabrics in terms of their power budget, and the analysis of the port count and of the aggregate bandwidth offered by these architectures to build Terabit packet switches.