Netgear FSM726S user Manual
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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.
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Port trunking is used to aggregate multiple switch ports into one full-duplex, high-
bandwidth 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
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- 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.
Campus backbone Connect building switches to a central campus switch.
High-Performance
Deliver a high-speed connection to powerful computers.
Servers
Power Users Provide high bandwidth to the desktop for multimedia and other
data-intensive applications.
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:
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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.
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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.
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