Scaling Ethernet speeds to 100 Gbits/s and beyond

Dramatic growth in Internet Protocol (IP) traffic demand is driving the need for new high-bandwidth IP interfaces. Today, router-to-router and router-to-transport system connections using Ethernet interfaces are limited to 10 Gbits/s (10GE) or slower. Although techniques, such as link aggregation, allow a limited degree of extensibility beyond 10 Gbits/s, they are limited in terms of scalability, introduce additional complexity, and reduce throughput efficiency. Discussion now centers on defining an Ethernet architecture that meets the needs of carriers and is conducive to implementation by the switch and server vendors. In this paper, we consider aggregation at the physical layer (APL) as a means to reuse existing 10GE physical layers (PHYs), while offering interface scalability to 100 Gbits/s and beyond. With APL, aggregation is performed at the PHY, whereby full Ethernet frames are transmitted across the aggregated PHYs in a parallel fashion. This ensures equal utilization of all links and allows aggregate bandwidth between nodes to scale with each new link added. We have demonstrated the applicability of such an approach by implementing a 100 Gbits/s interface using off-the-shelf components and running it over a live 4,000 km backbone network of a tier-1 Internet service provider.