Scaling Internet Routers Using Optics

This paper introduces the use of optical technology inside routers to increase their capacity and enable it to keep up with the rapid growth in Internet traffic. Despite the expected growth of router capacity, traffic will likely outgrow it and balloon in comparison within a decade. In describing the problems of existing multi-rack routers, the authors reveal the need for a scalable solution that guarantees 100% throughput. Having expressed the motivation behind the new technology, the authors initially present Chang's load-balanced switch architecture and explain how it satisfies the aforementioned requirements. To address the first major issue present in the load-balanced switch, the expensive optical switch fabric can be replaced by a single fixed mesh of optical channels. Here, the actual packet switching occurs in the intermediate linecards. Due to TCP's poor performance in the presence of out-of-order packets, the Full Ordered Frames First (FOFF) scheme is used to prevent packet mis-sequencing. The FOFF scheme is efficient, practical and has no pathological traffic patterns. The router must also be robust: it must support an arbitrary placement of an arbitrary number of linecards. This requires a reconfigurable switch that scatters traffic uniformly across the linecards. Here, the authors propose a hybrid electro-optical switch, as well a pure optical switch that should be implementable in the near future.

The primary obstacle for me throughout this paper was my limited knowledge of router internals such as linecards and racks. To an extent, I had to deduce what these terms meant from the early sections of the paper. Otherwise, this was an interesting read on router technology and the need to increase router capacity. I wouldn't say it's absolutely essential for the syllabus.