HP ML530 RDMA protocol: improving network performance - Page 2

Abstract Remote Direct Memory Access (RDMA) is a data exchange technology that improves network performance by streamlining data processing operations. This technology brief describes how RDMA can be applied to the two most common network interconnects, Ethernet and InfiniBand, to provide efficient throughput in the data center. Introduction Advances in computing and storage technologies are placing a considerable burden on the data center's network infrastructure. As network speeds increase and greater amounts of data are moved, it takes more processing power to process data communication. A typical data center today uses a variety of disparate interconnects for servers-to-servers and serverto-storage links. The use of multiple system and peripheral bus interconnects decreases compatibility, interoperability, and management efficiency and drives up the cost of equipment, software, training, and the personnel needed to operate and maintain them. To increase efficiency and lower costs, data center network infrastructure must be transformed into a unified, flexible, high-speed fabric. Unified high-speed infrastructures require a high-bandwidth, low-latency fabric that can move data efficiently and securely between servers, storage, and applications. Evolving fabric interconnects and associated technologies provide more efficient and scalable computing and data transport within the data center by reducing the overhead burden on processors and memory. More efficient communication protocols and technologies, some of which run over existing infrastructures, free processors for more useful work and improve infrastructure utilization. In addition, the ability of fabric interconnects to converge functions in the data center over fewer, or possibly even one, industrystandard interconnect presents significant benefits. Remote direct memory access (RDMA) is a data exchange technology that promises to accomplish these goals and make iWARP (a protocol that specifies RDMA over TCP/IP) a reality. Applying RDMA to switched-fabric infrastructures such as InfiniBand™ (IB) can enhance the performance of clustered systems handling large data transfers. Limitations of TCP/IP Transmission Control Protocol and Internet Protocol (TCP/IP) represent the suite of protocols that drive the Internet. Every computer connected to the Internet uses these protocols to send and receive information. Information is transmitted in fixed data formats (packets), so that heterogeneous systems can communicate. The TCP/IP stack of protocols was developed to be an internetworking language for all types of computers to transfer data across different physical media. The TCP and IP protocol suite includes over 70,000 software instructions that provide the necessary reliability mechanisms, error detection and correction, sequencing, recovery, and other communications features. Computers implement the TCP/IP protocol stack to process outgoing and incoming data packets. Today, TCP/IP stacks are usually implemented in operating system software and packets are handled by the main (host) processor. As a result, protocol processing of incoming and outgoing network traffic consumes processor cycles-cycles that could otherwise be used for business and other productivity applications. The processing work and associated time delays may also reduce the ability of applications to scale across multiple servers. As network speeds move beyond 1 gigabit per second (Gb/s) and larger amounts of data are transmitted, processors become burdened by TCP/IP protocol processing and data movement. The burden of protocol stack processing is compounded by a finite amount of memory bus bandwidth. Incoming network data consumes the memory bus bandwidth because each data packet 2