Introduction
Bandwidth is getting cheaper. Technical innovation in software, protocols, and hardware has pushed data networks to new heights of performance, while attacking costs aggressively. Fast links are available today for a fraction of what far slower connections cost a mere decade ago. While bandwidth may never be "too cheap to meter," as was promised for nuclear power, technological developments may make regulating bandwidth more like regulating the use of copy machines or pencils. Some day, it may hardly be worth the effort to monitor network usage except in cases of gross abuse, or as a fee-collection mechanism in lawyers' offices.
At the same time, new applications are placing increasing demands on the network. We invent new ways of using the network infrastructure as fast as we can deploy it. Networks are called upon to support myriad voice, video, and interactive applications alongside traditional data systems, each of which must run in concert with the objectives of the organization.
Now that the network is a part of the business infrastructure, we need control systems to make it toe the line. The network has to meet the same requirements as other parts of the company: increased effectiveness and reduced costs.
Increased effectiveness means faster customer service, quicker dissemination of information, and so on. It means access to more current information. It means clear, accurate communications systems that are integrated with the reliable operation of business-critical applications.
Reduced costs can come from more efficient use of existing resources, lower costs of expansion, or delayed expenditures. The ability of data networks to supplant other critical infrastructures, such as office or long-distance telephony, means that networks can reduce costs substantially. Careful management of costly wide-area-network (WAN) links can delay the inevitable bandwidth upgrades, further lowering the organization's expenses.
IT managers have only recently begun to think in business terms. For many IT organizations, the business objectives of the network are now becoming obvious. To succeed in an information age, companies must translate their business practices into network behaviors and information architectures, designing the network for specific business goals and objectives.
This book is about managing bandwidth and quality of service in enterprise networks. The discussion will take us into the realm of real-time classification and packet handling as well as into the systems and processes that are part of building and maintaining a bandwidth-managed network.
The Internet began with the premise that discrete chunks of data travel across a network of routers without the involvement of the end nodes. This meant that the sender and receiver were "smart" and the intermediate network was "dumb." This model allowed the Internet to grow at an amazing pace. Unfortunately, it also led to a service-poor network infrastructure in which the onus was on the end nodes to provide any of the services an application might need. Traffic might be lost, rerouted, or delayed during transmission, and it was left to the sender and receiver to sort things out. Unlike circuit-switched or packet-switched networks, routed networks like IP offer none of the determinism we need — in return for optimal use of available bandwidth.
As we introduce new applications onto IP networks, we place new demands on the network. We need high performance, low delay, and consistent behavior from a best-effort network so that we can deploy multimedia and mission-critical systems. Consequently, IP's simplicity is an obstacle to certain applications. Bandwidth management systems allow us to regulate the performance of a network and share bandwidth equitably across various applications and users.
At the same time, we don't want to sacrifice the simplicity that has brought us this far. Successful QOS solutions will be those that implement a few changes and have far-reaching effects. This book is about such solutions.
Consequently, IP's simplicity is an obstacle to certain applications. Bandwidth management systems allow us to regulate the performance of a network and share bandwidth equitably across various applications and users.
At the same time, we don't want to sacrifice the simplicity that has brought us this far. Successful QOS solutions will be those that implement a few changes and have far-reaching effects. This book is about such solutions. Intended audience
This book covers the issues surrounding quality of service in enterprise networks and the Internet. It assumes some degree of knowledge about general networking concepts, and provides a foundation for understanding bandwidth management mechanisms. It is suited for a variety of readers, including:
Network engineers, architects, and managers seeking a consolidated book from which to learn about Quality of Service (QOS) and policy-based networking.
People charged with implementing QOS systems in products or applications, including product managers, sales engineers, and network system integrators.
CIO's and senior IT managers who are responsible for assuring the competitive capability of their information systems and allocating budgets and personnel to the deployment of next-generation networking infrastructures. Acknowledgments
The elegant design of networking protocols such as TCP has taken them far beyond their intended goals, and ushered in a new era of communication worldwide. The simplicity and elegance of these designs is to be applauded. We owe our thanks to the thousands of engineers who work to push the envelopes of networking in private companies and standards bodies worldwide. QOS is a complex and still subjective area. Rod Anderson, Lionel Gibbons, Elaine Lusher, Paul Mokapetris and Mark Roy helped with structure and technical insight and are responsible for substantial improvements and clarifications in the text.
Any errors, omissions, or oversights are ours alone. Recent Developments
The field of QOS is dynamic and constantly changing. To provide you with current information and links to relevant standards, we maintain a site dedicated to QOS work and standards at networkshop.ca/QOS.
Back Cover Copy
The definitive guide to policy-based IP traffic management shows you how to guarantee the performance of mission-critical Internet applications!
To build networks that support today's mission-critical applications without breaking the bank, it's no longer enough to simply add bandwidth. You must manage it more effectively, as well. Managing Bandwidth is the first complete guide to next-generation Quality of Service (QOS) techniques for cutting costs, enhancing performance, deploying next-generation applications, handling peak loads, and maximizing the value of your enterprise network. You'll understand and compare your latest QOS options, discover workarounds for the limitations of today's standards, plan your long-term bandwidth management strategy, and more:
- Understand various QOS approaches, including media prioritization and the Integrated Services and Differentiated Services models.
- Deploy load-balancing and caching alternatives that mitigate server load and increase end-to-end application performance.
- Compare the performance requirements of your applications: data, voice, video, and beyond.
- Implement policy systems and service level agreements for scalable distribution and tracking of QOS rules.
- Give "A-list" customers preferred access to Internet and network resources.
- Integrate QOS with enterprise directory services such as Directory-Enabled Networks and directory access protocols like LDAP.
- Monitor real-world network service levels in a QOS environment.
- Learn when to "throw bandwidth at the problem" instead of worrying about QoS.
You'll also find seven real-world case studies of bandwidth-managed networks, ranging from single-site small businesses to global financial institutions.
IP QOS is a vital component of a modern network. Managing Bandwidth gives you the critical information you need to start reaping its business benefits now-before your competitors do!
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