Increasing Network Resiliency by Optimally Assigning Diverse Variants to Routing Nodes

Networks with homogeneous routing nodes are constantly at risk as any vulnerability found against a node could be used to compromise all nodes. Introducing diversity among nodes can be used to address this problem. With few variants, the choice of assignment of variants to nodes is critical to the overall network resiliency. We present the Diversity Assignment Problem (DAP), the assignment of variants to nodes in a network, and we show how to compute the optimal solution in medium-size networks. We also present a greedy approximation to DAP that scales well to large networks. Our solution shows that a high level of overall network resiliency can be obtained even from variants that are weak on their own. We provide a variation of our problem that matches the specific communication requirements of applications run over the network (e.g., Paxos and BFT). Also, we analyze the loss in resiliency when optimally assigning variants based on inaccurate information about compromises.