Memory-efficient and scalable virtual routers using FPGA

Router virtualization has recently gained much interest in the research community. It allows multiple virtual router instances to run on a common physical router platform. The key metrics in designing network virtual routers are: (1) number of supported virtual router instances, (2) total number of prefixes, and (3) ability to quickly update the virtual table. Limited on-chip memory in FPGA leads to the need for memory-efficient merging algorithms. On the other hand, due to high frequency of combined updates from all the virtual routers, the merging algorithms must be highly efficient. Hence, the router must support quick updates. In this paper, we propose a simple merging algorithm whose performance is not sensitive to the number of routing tables considered. The performance solely depends on the total number of prefixes. We also propose a novel scalable, high-throughput linear pipeline architecture for IP-lookup that supports large virtual routing tables and quick non-blocking update. Using a state-of-the-art Field Programmable Gate Array (FPGA) along with external SRAM, the proposed architecture can support up to 16M IPv4 and 880K IPv6 prefixes. Our implementation shows a sustained through-put of 400 million lookups per second, even when external SRAM is used.