4500 Great America Parkway · Santa Clara, CA 95054 Switch Management: Why Your Small Business Needs It, February 1, 2002 Small-business networking environments are more powerful than ever. From e-mail to office suites and mission-critical applications, networks give employees the tools to do their jobs, while providing small businesses with the performance and flexibility they need to be agile competitors in today's challenging global marketplace. To remain competitive, small businesses are equipping their employees with desktop personal computers (PCs), notebook PCs, and an Information Technology (IT) infrastructure in an effort to maximize productivity while lowering total operating expenses. In reality, most small businesses with 250 or fewer employees cannot take full advantage of their networked environment unless it can be managed simply, effectively, and affordably. Otherwise, the total costs of ownership (TCO) can spiral out of control, preventing small businesses from realizing the full value of their environment. Among the hidden costs of a poorly managed small-business network are: Lost time due to excessive network downtime. Low productivity due to bottlenecks and poor understanding of network traffic patterns. Configuration and management tools which are difficult to use. Adopting a managed solution that forces customers into buying high-priced products from a single network vendor to ensure interoperability with their existing investment. This limitation prevents customers from mixing and matching best-of-breed products from different vendors, which can offer greater capabilities at a lower cost than a solution they are locked into. Contrast the points above to a well-managed small-business network that has adopted a managed-switch solution specifically designed for small businesses. In this environment: Switch and traffic monitoring help head off problems before they occur, reducing user downtime. Management tools offer an intuitive graphical user interface (GUI) that simplifies configuration and monitoring tasks. Management functions can be performed remotely using a web browser or directly via a console directly connected to the switch. 1 Port trunking is used to aggregate multiple switch ports into one full-duplex, highbandwidth port for greater throughput. The IEEE802.1d Spanning Tree Protocol is used to enhance network resilience to link failures and protect networks against loops. Switch firmware can be upgraded through TFTP to take advantage of new features and improvements. As network-centric applications, file sizes, Internet traffic, network users, and the need for instant access to data all continue to increase, small-businesses will continue to be impacted by the resulting network bandwidth crunch. Because network availability has a dramatic impact on the success of small businesses more and more small businesses will be turning to a managedswitch solution for their networks. Managed switches designed for small businesses offer plug-and-play installation and easy maintenance, with basic and advanced features that stand up to the bandwidth demands of today. Managed switches also hold the key to the emerging capabilities that small-business networks are expected to provide, now and in the future. This white paper shows how small businesses can benefit from a managed switch. It describes the basic and advanced management features found in managed switches, and provides practical suggestions for putting managed switches to work for you. A glossary at the end of this paper defines the technical terms used in this paper (these terms are italicized when mentioned for the first time). What is a Managed Switch? The network is a vital component of any small business. Without the network, even the best servers, applications, and databases are effectively useless. The one common element of all aspects of any IT infrastructure is the underlying network. A managed switch allows the ports on the switch to be configured, monitored, enabled, and disabled. Switch management can also gather information on a variety of network parameters, such as: The numbers of packets that pass through the switch and each of its ports. What types of packets they are. Whether the packets contain errors. The number of collisions that have occurred. Basic Management Features of a Managed Switch Switches come with a variety of features. The following sections describe basic features that a small business should look for in a managed switch. These sections include: - Gigabit Ethernet Support - Port Monitoring - Central/Remote Monitoring 2 - Detecting Packet Errors Fault Isolation Capacity Planning Port Control- Speed, Mode, and Flow Control Gigabit Ethernet Support Gigabit Ethernet has emerged as an easy and inexpensive solution for networks straining under the weight of increased network traffic. Gigabit Ethernet offers high-speed 1 Gbps (1000 Mbps) operation, which is 10 times faster than the 100 Mbps speed of Fast Ethernet. All network services and protocols written for 10 and 100 Mbps Ethernet networks work unchanged over Gigabit Ethernet. These similarities allow Gigabit Ethernet to be easily implemented into, and coexist with, existing Ethernet and Fast Ethernet networks. For this reason, small businesses deciding on a managed-switch solution should choose a managed switch that supports Gigabit Ethernet even if they currently use Ethernet or Fast Ethernet. Furthermore, small businesses can combine Gigabit Ethernet with other low- or highbandwidth technologies to structure the environment best suited to their requirements. The following table provides application examples. Table 1. Examples of Switch Applications Using Gigabit Ethernet Building backbone Connect a central Gigabit Ethernet switch with centrally located servers and with workgroup and department switches located in wiring closets. Connect building switches to a central campus switch. Deliver a high-speed connection to powerful computers. Provide high bandwidth to the desktop for multimedia and other data-intensive applications. Campus backbone High-Performance Servers Power Users Port Monitoring One of the core objectives of switch management is its ability to monitor the number of data packets sent or received on every switch port. Determining which ports are being used more than others allows companies to identify traffic patterns, monitor network trends, and determine appropriate bandwidth needs so that the appropriate changes can be made to the network to increase performance and efficiency. By monitoring switch ports continuously, port monitoring also provides companies with the assurance that ports are working properly and are available to users. It also makes it possible to identify port congestion and port failures, minimizing their potential impact on users and the business as a whole. Some port monitoring features also monitor the types of packets sent and received on switch ports. These data packet types include: 3 Unicast packets data packets with a single destination address. Unicast packets are sent from a single source to a single destination. This node-to-node transmission method is the predominant form of transmission on Local Area Networks (LANs) and across the Internet. Multicast packets data packets sent to a selected group of recipients. Broadcast packets data packets sent to everyone on the network. Central/Remote Port Monitoring Managed switches can contain embedded software or come with installable software that allows ports to be monitored centrally and/or remotely. Central port monitoring, as its name implies, provides a central point of control. With this monitoring method, client software is installed on a central workstation or PC. With this software, the health and performance of managed switch ports can be monitored from a central management console, without having to go to the switch's physical location. Remote port monitoring allows ports to be monitored using a Web browser or SNMP-based solutions: Web-based monitoring allows switch ports to be monitored over the Internet. Switches that support web-based monitoring include software for assigning an Internet Protocol (IP) address to the switch. Once the IP address is assigned, you can access the switch from any PC or workstation that has an Internet connection and a Web browser. SNMP-based solutions enable industry-standard SNMP and RMON management methods to be used from any network-management application or in-band via Telnet. SNMP and RMON management methods are described later in this paper. Detecting Packet Errors In addition to detecting data packets, managed switches can detect and record errors associated with data packets that a port sends or receives. Some network-management tools alert administrators to problems like excessive packet errors or bandwidth overload on a segment. Other tools can perform simple baselining, such as computing packets per second versus collisions per second on a per-port basis. While the number and types of packet errors that can be tabulated varies between networkmanagement applications, typical errors include: Undersize packets packets smaller than the minimum size defined for IEEE 802.3 packets. Oversize packets packets that exceed the maximum length defined for IEEE 802.3 packets. Jabbers packets that a port receives from a faulty device that transmits oversize packets continuously. Fragments incomplete data packets that a port sends or received. Packets that contain a Cyclic Redundancy Check (CRC) or alignment error, which means the data was corrupted during transmission. 4 Fault Isolation A fault is a condition that impedes the flow of traffic across the network. Fault isolation, as its name implies, is the ability to locate the source of a failure and isolate it before it impacts network communications. Managed switches that support fault isolation can identify potential and actual problems caused by various factors, such as traffic patterns, traffic congestion, and port status. Capacity Planning Change is the one constant in small-business networking environments, where new applications and new users are continually being added. Despite the dynamic nature of their networks, most small businesses lack the in-house expertise to determine what resources will be required to provide adequate network stability and performance, at a reasonable price, 45, 30, even 15 days from today. Worse, most small businesses can't budget against a guess. For this reason, some managed switches support capacity planning. These features allow small businesses to obtain a good reading of their current networking requirements so they can ascertain the viability of future solutions. The objective of capacity planning is to analyze current workloads and reserve capacity, and provide estimates of workload growth and sizing of new applications. Based on that information, estimates of the resources required to support future workloads can be estimated. With capacity planning, small businesses can: Measure their current network capacity For example, determine which switch ports handle the most network traffic and which handle the least and at which times. Understand how changes affect their network For example, how adding users and applications affect the network. In some cases, small businesses may need to add more network capacity or upgrade their hardware (such as moving from Ethernet or Fast Ethernet to Gigabit Ethernet) to handle these changes. In other cases, they might be able to accommodate the changes within the current network. Identify network capacity changes As more users and resources are added to the network, small businesses can identify changes and trends in network capacity and utilization patterns and identify network service-improvement opportunities. Plan for growth based on future resource requirements As you become more familiar with your network capacity and the factors that affect growth, and learn how to recognize changes and trends, you can proactively plan for network growth. In this way, capacity planning allows small businesses to determine where and when to add new capacity, stay ahead of their networking needs, justify purchases more easily, and deploy existing solutions more efficiently. 5 Port Control - Speed Managed switch ports support auto-sensing and manual configuration. Auto-sensing enables switch ports to automatically operate at the fastest speed possible, depending on the speed of the attached device. Some newer switches even provide 1000 Mbps (1 Gbps) auto-sensing ports. Small businesses especially those on a tight budget may decide to postpone their purchase of new technologies until the price comes down. Until that time arrives, these businesses will continue using their legacy devices. Certain legacy devices, however, may not support auto-sensing. Auto-sensing switch ports connected to these devices are unable to ascertain the at ...