FlashTrie: Hash-based Prefix-Compressed Trie for IP Route Lookup Beyond 100Gbps

It is becoming apparent that the next generation IP route lookup architecture needs to achieve speeds of 100-Gbps and beyond while supporting both IPv4 and IPv6 with fast real-time updates to accommodate ever-growing routing tables. Some of the proposed multibit-trie based schemes, such as Tree Bitmap, have been used in today´s high-end routers. However, their large data structure often requires multiple external memory accesses for each route lookup. A pipelining technique is widely used to achieve high-speed lookup with a cost of using many external memory chips. Pipelining also often leads to poor memory load-balancing. In this paper, we propose a new IP route lookup architecture called FlashTrie that overcomes the shortcomings of the multibit-trie based approach. We use a hash-based membership query to limit off-chip memory accesses per lookup to one and to balance memory utilization among the memory modules. We also develop a new data structure called Prefix-Compressed Trie that reduces the size of a bitmap by more than 80%. Our simulation and implementation results show that FlashTrie can achieve 160-Gbps worst-case throughput while simultaneously supporting 2-M prefixes for IPv4 and 279-k prefixes for IPv6 using one FPGA chip and four DDR3 SDRAM chips. FlashTrie also supports incremental real-time updates.