Searching very large routing tables in wide embedded memory

Abstract

Exponentially growing routing tables create the need for increasingly storage-efficient lookup schemes that do not compromise on lookup performance and update rates. This paper evaluates the mechanisms that determine the storage efficiency of state-of-the-art IP lookup schemes. A novel scheme named BARTS (Balanced Routing Table Search) Is proposed for searching large routing tables in wide embedded memory at OC-192 and OC-768 speeds, while also supporting fast incremental updates. BARTS supports a 38K-entry routing table in 255 KB and a 72K-entry table in 453 KB; a 500K-entry table is estimated to fit into 3 MB. More sophisticated memory management can further reduce these figures to 215, 375 KB, and approx. 2.5 MB, respectively. This is sufficient to handle the large routing tables towards which the Internet seems to be heading in the near future.