High-Performance Networking Unleashed -- Table of Contents High-Performance Networking Unleashed Table of Contents: Part I - Planning Your Infrastructure: What You Need to Know · Chapter 1 - Introduction to High-Performance Networking · Chapter 2 - The Physical Layer · Chapter 3 - Frame Types · Chapter 4 - Internetworking Protocol Stacks Part II - Bringing Your Lines Together · Chapter 5 - LAN Topologies · Chapter 6 - Hubs · Chapter 7 - Bridges · Chapter 8 - Switches · Chapter 9 - Routers · Chapter 10 - Gateways Part III - Selecting the Right WAN · Chapter 11 - Selecting the Right WAN · Chapter 12 - POTS · Chapter 13 - ISDN · Chapter 14 - xDSL · Chapter 15 - Switched 56Kbps · Chapter 16 - T-1 and Fractional T-1 http://24.19.55.56:8080/test/ (1 of 2) [3/6/2001 11:03:02 PM] High-Performance Networking Unleashed -- Table of Contents · Chapter 17 - Frame Relay · Chapter 18 - Selecting the OS to Meet Your Needs Part IV - The Right OS for the Job · Chapter 19 - Selecting the OS to Meet Your Needs · Chapter 20 - UNIX/Linux · Chapter 21 - Windows NT 4 · Chapter 22 - NetWare Part V - Putting It All Together · Chapter 23 - Improving an Existing Network · Chapter 24 - Building a New Network from Scratch · Chapter 25 - Internetworking Operating Systems · Chapter 26 - Clustering · Chapter 27 - Multimedia Communication Part VI - Maintaining Your Network · Chapter 28 - Monitoring Your Network · Chapter 29 - Administering Your Network · Chapter 30 - Looking to the Future http://24.19.55.56:8080/test/ (2 of 2) [3/6/2001 11:03:02 PM] High-Performance Networking Unleashed -- Ch 1 -- Introduction to High-Performance Networks High-Performance Networking Unleashed - 1 - Introduction to High-Performance Networks by Mark Sportack and Keith Johnson The past decade has been witness to the radical evolution of data networks from their humble origins to their current forms. The original Local Area Networks (LANs), were nothing more than coaxial cabling, strung from terminal servers to desktop terminals whose users were treated to monochromatic text displayed on low-resolution cathode ray tubes (CRTs). In the mid-1980s, wide area networks (WANs), too, were slow and crude. Terminal servers multiplexed access for dozens of users to 9.6Kbps circuits. These circuits connected users to mainframe-based applications that lay hidden in a remote data center. Today, LANs have metamorphosed into high-bandwidth, high-performance, local area networks that support bandwidth- and CPU-intensive client applications such as live, interactive voice and videoconferencing, as well as e-mail and some of the more traditional forms of data processing. WANs, too, have experienced radical, evolutionary change. Today, 9.6Kbps is deemed inadequate for most of the needs of even a single user. Just try to give a user a 9.6Kbps modem for use as anything but a paperweight! It is important to recognize that the impetus for all these changes has been, and remains, the user's business requirements. The competitive environment of most business entities ensures that any technological innovations that offer competitive advantages--that is, better, cheaper, and/or faster--get accepted. For example, the introduction of the mouse facilitated access to computing by obviating the need for typing skills. Suddenly, almost everyone could use a computer! Personal computers, too, offered countless advantages by distributing intelligence down to the desktop. Software developers also drove changes by constantly upgrading a dizzying array of increasingly complex products that enabled users to actually use the newly distributed processing power at their fingertips. Together, these innovations quickly made hard-wired connections to terminal servers obsolete. http://24.19.55.56:8080/test/ch01\ch01.htm (1 of 25) [3/6/2001 11:03:18 PM] High-Performance Networking Unleashed -- Ch 1 -- Introduction to High-Performance Networks Into this void came the first generation of LANs. These networks offered almost obscene amounts of bandwidth, such as 1 or 4Mb per second (Mbps), depending on whose network you purchased. Initially, these LANs were used as a more flexible means of connecting users with terminal servers. After all, the users' basic requirements hadn't changed all that much, and the increased bandwidth was more than adequate to support terminal emulation. Towards the end of the 1980s, this first generation of LANs began to show its age. Once the user community understood that the distributed microprocessors on their desktops could do more than just terminal emulation, their quest for even more bandwidth and for higher performance networking began. The second generation of LANs were little more than faster versions of their predecessors. 1Mbps Ethernets grew into 10Mbps Ethernets. Similarly, 4Mbps Token Rings were accelerated to 16Mbps. This increase in the clock rates would keep users somewhat satisfied up to the middle of the 1990s. The mid-1990s witnessed the maturation of both Ethernet and Token Ring. Unlike the first generation LANs, however, the resulting performance crisis was not caused solely by a lack of bandwidth. On Ethernet networks, in particular, insufficient bandwidth was not the problem. Rather, performance degradation was typically due more to either · Excessive competition for access to the LAN, or · Saturation of the available bandwidth with unnecessary broadcasts. In either event, an increase in the clock rate would only have masked the problem and postponed its solution. A better and more cost-effective approach would be to create more available bandwidth per user by installing switching hubs. Switching hubs segment a LAN's collision domain. That is, within the network's broadcast domain, switching hubs create multiple collision domains, each with their own bandwidth. This proved a more effective solution. New application types also demonstrated the limitations of the embedded base of networks. They demanded different performance parameters than their supporting networks were designed to provide. For example, in a traditional Ethernet-to-MVS (Multiple Virtual Storage, an IBM mainframe operating system) connection that traversed an Internet Protocol (IP) WAN, the data inside each packet had to be good. Corrupted data meant that the packet had to be present. New time-sensitive applications such as voice or videoconferencing, however, placed a higher importance on the timeliness of delivery than on data integrity. If the packet arrived intact, but two seconds late, it was discarded. Thus, traditional LANs show their maturity by failing to accommodate latency-sensitive traffic. User requirements are driving innovations in network protocols, too. Networking protocols are adding capabilities such as Quality of Service (QoS) support, bandwidth reservation, and so on, that allow today's networks to become truly high-performance networks by supporting time-sensitive applications as handily as they accommodate traditional bulk data requests. One of the more significant network protocols, IP, is about to receive its first major update in twenty years. The new protocol will be called IPv6, and will enable networks to adequately support evolving business requirements for many years to come. IPv6 and other network protocols are adding security features at the network layer. Features such as authentication and encryption that previously could only be implemented at the host level, will now be a http://24.19.55.56:8080/test/ch01\ch01.htm (2 of 25) [3/6/2001 11:03:18 PM] High-Performance Networking Unleashed -- Ch 1 -- Introduction to High-Performance Networks native part of the network. This will allow networks to be interconnected in ways that were previously unthinkable. "Open" IP networks of different companies will be directly internetworked in "extranets." These extranets will be functional extensions of corporate intranets that link business partners together in a secure, controlled fashion. As today's networks become faster and more feature rich, one other important change must occur. Traditionally, data communications experts stayed in the network layer, arrogantly dismissing applications, data, protocols, and so on, as nothing more than 1s and 0s in the stream. The increasing variety of applications, and the subsequent variety of network performance requirements, leaves no room for such aloofness. Today, data communications experts must venture further up the "stack," sometimes as far as the application layer. Their network skills must be augmented with at least a working knowledge of the applications that rely upon networks. More importantly, the specialized performance needs of these applications must be understood in order to unleash the power of high-performance networks. This book will take you step by step through all of the components that comprise a high- performance network, and provide you with everything you will need to begin building and running your own high-performance network. The Open Systems Interconnection (OSI) 7-layer reference model is used throughout this book as a context for examining the various components and functions of a network. This examination begins with the physical layer. Networking Glossary: 150+ Words You Should Know There are a lot of terms used in this book that many of our readers may not be familiar with. To help get you started, we are offering definitions of about 150 networking terms that you should be familiar with. 10base-2 The version of Ethernet that uses thin coaxial cable. The name is derived from the speed of the network (10Mbps), the