Harrick Vin

A programming environment for packet-processing systems: Design considerations

The programming environments-languages, compilers, and runtime systems -for NPs are in their infancy. At the same time, NPs represent a much larger trend in the processor industry: multicore, lightweight threaded architectures designed for throughput-driven applications. Once this trend hits the mainstream-programming marketplace, the need for a programming environment that is as easy to use as the programming environments for todays workstations and servers will become universally important to programmers. The Shangri-La architecture represents a complete programming environment for the domain of packet processing on multicore, lightweight threaded architectures in general, and NPs specifically. Shangri-La encompasses a language that exposes domain constructs instead of hardware constructs, keeping the programmer and code separate from architectural details; a sophisticated compiler complex that uses profile information to guide the mapping of code to processors and data structures to memory automatically; and runtime system to ensure maximum performance benefits in the face of fluctuating traffic conditions-both natural and malicious. Currently effort is being made on two major tasks: creating a prototype implementation of the proposed architecture, and researching the more difficult questions that will appear as development proceeds. The prototype system, which builds on the Open Research Compiler infrastructure and targets the Intel IXP2400 network processor, will provide a platform for further research and development.

Two stage packet classification using most specific filter matching and transport level sharing

In this paper we introduce two new concepts to the design of packet classification systems. First, we propose most specific filter matching (MSFM), an improvement over the well known Cross Producting algorithm [V. Srinivasan, S. Suri, G. Varghese, M. Waldvogel, Fast and scalable layer four switching, in: Proceedings of ACM SIGCOMM, 1998] that significantly reduces the memory requirement of the earlier scheme. Second, we suggest that rules specifying the same source-destination IP prefix pair can be grouped together forming shared sets of transport level fields. This property of Transport Level Sharing (TLS), which characterizes real world classification databases is exploited for reducing a classifiers memory requirement and for hardware acceleration. We split the classification process into two stages. First, we perform classification on source-destination IP prefix pairs using the MSFM algorithm. Second, we perform classification on transport level fields exploiting transport level sharing. It is the combination of most specific filter matching and transport level sharing which results in a scheme that requires no more than 11 dependent memory accesses in the critical path independent of the size of the classification database. The memory access bandwidth of our scheme is also bounded when our scheme is accelerated in hardware. Compared to other schemes which involve a small and predictable number of steps in the critical path (e.g., Cross Producting [V. Srinivasan, S. Suri, G. Varghese, M. Waldvogel, Fast and scalable layer four switching, in: Proceedings of ACM SIGCOMM, 1998] or Recursive Flow Classification [P. Gupta, N. McKeown, Packet classification on multiple fields, in: Proceedings of ACM SIGCOMM, 1999]) the combination of most specific filter matching and transport level sharing is associated with the least memory requirement.

A programming environment for packet-processing systems

The programming environments-languages, compilers, and runtime systems -for NPs are in their infancy. At the same time, NPs represent a much larger trend in the processor industry: multicore, lightweight threaded architectures designed for throughput-driven applications. Once this trend hits the mainstream-programming marketplace, the need for a programming environment that is as easy to use as the programming environments for todays workstations and servers will become universally important to programmers. The Shangri-La architecture represents a complete programming environment for the domain of packet processing on multicore, lightweight threaded architectures in general, and NPs specifically. Shangri-La encompasses a language that exposes domain constructs instead of hardware constructs, keeping the programmer and code separate from architectural details; a sophisticated compiler complex that uses profile information to guide the mapping of code to processors and data structures to memory automatically; and runtime system to ensure maximum performance benefits in the face of fluctuating traffic conditions-both natural and malicious. Currently effort is being made on two major tasks: creating a prototype implementation of the proposed architecture, and researching the more difficult questions that will appear as development proceeds. The prototype system, which builds on the Open Research Compiler infrastructure and targets the Intel IXP2400 network processor, will provide a platform for further research and development.