Scalable forwarding tables for supporting flexible policies in enterprise networks

With increasing demands for more flexible services, the routing policies in enterprise network becomes much richer. This has placed a heavy burden to the current router forwarding plane to support the increasing number of policies, primarily due to the limited capacity in TCAM. This hinders the development of new network services. In this paper, we present the design and implementation of a new forwarding table structure. It separates the functions of TCAM and SRAM and maximally utilizes the large & flexible SRAM. We progressively design a set of schemes, to maintain correctness, compress storage, and achieve line-card speeds. We also design incremental update algorithms that bring less accesses to memory. We present implementation designs and evaluate our scheme with a real implementation on a commercial router using real data sets. Our design does not require new devices. The evaluation results show that the performance of our forwarding tables is promising.