RIA: Trading Packet Headers for Packet Processing

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Washington University at St. Louis George Varghese RIA: Trading Packets Headers for Packet Processing In high speed networks, packet processing is relatively expensive while bandwidth is cheap. The central thesis here is that if suitable header fields can be added to packets, then mechanisms to speed up packet processing can be devised. Several ideas are advanced to support the above thesis. First, data manipulation (e.g. data copying, checksumming) is a major bottleneck of end system packet processing. The approach taken here suggests adding a data manipulation header to an easily accessible portion of each packet. This header contains pointers to fields (in various layers) required for data manipulation. This information (e.g. a pointer to data to be encrypted) allows implementations to efficiently combine data manipulation steps (e.g. encryption and copying). Prior work has shown that combining data manipulation steps can yield order-of-magnitude performance improvement. The present approach can yield similar improvements in a more uniform and structured fashion. Second the work studys adding index fields to protocol identifiers at all layers (e.g. connection identifiers, network addresses) to reduce lookup costs and generic protocol processing. Several new ides to utilize these index fields (threaded indexing, index passing, and source hashing) are studied. It is known that the use of Virtual Circuit Identifiers (VCIs) on virtual circuit packets simplifies lookup and packet processing. In source hashing and threaded indexing, the added indices essentially serve as VCIs, but for flows in a datagram network. In source hashing, for example, the "VCI" is a consistent random label chosen by the source. OUr new methods provide the benefits of normal VCis without requiring a round trip delay for set up. The methods can lower uorst case datagram lookup times form O(log(n) to O(1), which may be important for gigabit routers. IN this project we design, analyze, and implement these new ideas and search for other techniques that arise from the basis thesis. The current climate of transition (in which transport, routing, and data link protocols are changing) provides an opportunity to apply these techniques to influence real protocols.