Balancing Cost and Reliability in the Design of Internet Protocol Backbone Using Agile Optical Networking

To address reliability challenges due to failures and planned outages, Internet Service Providers (ISPs) typically use two backbone routers (BRs) at each central office. Access routers (ARs) are connected to these BRs in a dual-homed configuration. To provide reliability through node and path diversity, redundant backbone routers and redundant transport equipment to interconnect them are deployed. However, deploying such redundant resources increases the overall cost of the network. Hence, to avoid such redundant resources, a fundamental redesign of the backbone network leveraging the capabilities of an agile optical transport network is highly desired. In this paper, we propose a fundamental redesign of IP backbones. Our alternative design uses only a single router at each office. To survive failures or outages of a single local BR, we leverage the agile optical transport layer to carry traffic to remote BRs. Optimal mapping of local ARs to remote BRs is determined by solving an Integer Linear Program (ILP). We describe how our proposed design can be realized using current optical transport technology. We evaluate network designs for cost and performability, the latter being a metric combining performance and availability. We show significant reduction in cost for approximately the same level of reliability as current designs.