PCI Manual for the Design of Hollow Core Slabs

Abstract

Network operators would like their network to support cur- rent and future tra±c matrices, even when links and routers fail. Not surprisingly, no backbone network can do this today: It is hard to ac- curately measure the current matrix, and harder still to predict future ones. Even if the matrices are known, how do we know a network will support them, particularly under failures? As a result, today's networks are designed in a somewhat ad-hoc fashion, using rules-of-thumb and crude estimates of current and future tra±c. Previously we proposed the use of Valiant Load-balancing (VLB) for backbone design. It can guarantee 100% throughput to any tra±c ma- trix, even under link and router failures. Our initial work was limited to homogeneous backbones in which routers had the same capacity. In this paper we extend our results in two ways: First, we show that the same qualities of service (guaranteed support of any tra±c matrix with or without failure) can be achieved in a realistic heterogeneous back- bone network; and second, we show that VLB is optimal, in the sense that the capacity required by VLB is very close to the lower bound of total capacity needed by any architecture in order to support all tra±c matrices.