HP LH4r HP IA-32 Server Long Distance Cluster Interconnect for Windows Phase 1 - Page 3

FDDI The Fiber Distributed Data Interface (FDDI) was the first high speed LAN to be fully standardized. It defines a 100Mbps, token passing, and dual ring network using a fiber-optic transmission media. It is similar in many ways to Token Ring, including topology, media-access technique and reliability (redundant rings). FDDI is stable and mature as compared to other high-speed LAN technologies, but the versions of these that are comparable in speed to the Gigabit version of Ethernet are more costly. Disadvantages of traditional FDDI Networks are: • High latency (due to FDDI -> Ethernet/Ethernet -> FDDI translation) • No full duplex • Expensive Ethernet and Fast Ethernet Three networking topologies defined early networking: Ethernet, ArcNet, and Token Ring. Of these three, Ethernet emerged as the industry standard for most applications. Ethernet is 10Mbps, and its specifications are widely documented. FDDI provided much of the technical basis for the development of Fast Ethernet. Fast Ethernet is a 100Mbps technology that is currently supported by almost all of the major networking hardware vendors and has been accepted as the IEEE 802.3u standard. Despite that both Ethernet and Fast Ethernet provide sufficient bandwidth necessary for the heartbeat signal in general, the absence of fiber-optic media support precludes using these technologies for the purposes of long distance cluster interconnects. Gigabit Ethernet Gigabit Ethernet strongly outperforms competing network technologies such as Ethernet and Fast Ethernet, even with early versions of the hardware and software while also supporting fiber-optic media. Gigabit Ethernet uses the same frame format found in Ethernet and Fast Ethernet. Because the frame format and size are the same for all Ethernet technologies, no other network changes are necessary when moving from 10 or 100Mbps Ethernet protocols. This upgrade path allows Gigabit Ethernet to be seamlessly integrated into existing Ethernet and Fast Ethernet networks. In contrast, other high-speed technologies use fundamentally different frame formats. According to the current Gigabit Ethernet specifications, the technology can be deployed up to 550m over multimode fiber using short wave lasers with a preferred core size of 50 microns, and up to 5Km over 10um, 1300nm, single-mode fiber cable. Some sources claim that the technology can actually stretch up to 10Km and has the potential to reach 50Km or even more under the 9um, 1550nm fiber optic specifications. Pulling Gigabit Ethernet at such long distances though would probably require more powerful laser transducers and more sensitive receivers, and has yet to be thoroughly investigated. Extending the cluster interconnect up to 10Km is covered in Phase Two of this project. The main benefits of Gigabit Ethernet include: • Full duplex capacity • Native TCP/IP support • Increased bandwidth compared to Fast Ethernet technology that allows high performance communications without introducing bottlenecks in communication links • Low cost of ownership and implementation VIA The goal of Virtual Interface Architecture is to improve the performance of distributed applications in clusters of servers and workstations by reducing the latency associated with CPU processing load. VIA eliminates this overhead by moving the network interface much closer to the application. VI over IP At the time of this writing, Emulex Corporation has announced the GN9000/VI PCI Host Bus Adapter that is the industry's first implementation of the Virtual Interface (VI) architecture over TCP/IP protocol. It adds the speed and efficiency of VIA to standard Gigabit Ethernet environments, enabling IP networks to perform faster and more efficiently. This new combination of technologies introduces the speed of Gigabit Ethernet and low latencies of VI architecture, and supports existing multi-mode optical cables, allowing interconnect distances up to 550m. 3