Requirements and limitations of optical interconnects for high-capacity network elements

Architecture of network elements such as large routers and switches is becoming more and more complex due to the constantly increasing requirements on both capacity and performance. Already today, high-performance routers having capacities of more than several Tb/s can not be packaged in a single rack of equipment. Complex and spatially distributed multirack routers comprising a large number of line cards, switching modules and highspeed ports have already become reality. A consequence of this trend is that internal interconnecting system also becomes large and complex. Interconnection distances, total number of cables and power consumption increase rapidly with the increase in capacity, which can cause limitations in scalability of the whole system. This paper addresses requirements and limitations of large-scale optical interconnects. In particular, we investigated various point-to-point interconnects and two optically switched interconnection options with regard to their scalability by taking into account various optical signal impairments, number of fiber links and total power consumption.