interconnection mesh, and core routers as the "line cards". Such an implementation suffers from having all latencies increased to twice the worst-case transmission latency. But it has a number of intriguing advantages: Large backbone packet networks typically have massive overcapacity (10x or more) to deal with imperfect capacity planning, congestion, and other problems. A load-balanced switch backbone can deliver 100% throughput with an overcapacity of just 2x, as measured across the whole system. The underpinnings of large backbone networks are usually optical channels that cannot be quickly switched. These map well to the constant-rate 2R/N channels of the load-balanced switch's mesh. No route tables need be changed based on global congestion information, because there is no global congestion. Rerouting in the case of a node failure does require changing the configuration of the optical channels. But the reroute can be precomputed (there are only a finite number of nodes that can fail), and the reroute causes no congestion that would then require further route table changes. References External links Optimal Load-Balancing I. Keslassy, C. Chang, N. McKeown, and D. Lee Scaling Internet Routers Using Optics I. Keslassy, S. Chuang, K. Yu, D. Miller, M. Horowitz, O. Solgaard, and N. McKeown Computer networking Media access control