Payload Caching: High-Speed Data Forwarding for Network Intermediaries

Large-scale network services such as data delivery often incorporate new functions by interposing intermediaries on the network. Examples of forwarding intermediaries include rewalls, content routers, protocol converters, caching proxies, and multicast servers. With the move toward network storage, even static Web servers act as intermediaries to forward data from storage to clients. This paper presents the design, implementation, and measured performance of payload caching, a technique for improving performance of host-based intermediaries. Our approach extends the functions of the network adapter to cache portions of the incoming packet stream, enabling the system to forward data directly from the cache. We prototyped payload caching in a programmable highspeed network adapter and a FreeBSD kernel. Experiments with TCP/IP traÆc ows show that payload caching can improve forwarding performance by up to 60% in realistic scenarios.