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4500 Great America Parkway • Santa Clara, CA 95054
Small Business Stackable Switch White Paper January 16, 2001
Today’s fast-paced global business arena, spurred by the Internet and
World Wide Web (WWW), has changed the ground rules for small offices,
requiring them to work faster, be more responsive to customers, and
outpace a worldwide range of competitors. At the same time, the Internet
and WWW have also provided new ways for small offices to not only
survive ? but thrive ? in these market conditions.
To take advantage of today’s unprecedented opportunities, small offices
are deploying larger networks, higher -performance personal computers
(PCs) and servers, and resource-hungry client/server applications that
consume large amounts of bandwidth to support Internet- and/or intranetbased customer transactions or other business activities. At the same
time, small offices are facing the growing challenge of providing users
with sufficient bandwidth to perform day -to-day activities such as:
• Acc essing e-mail, the Internet, and the company intranet
• Fetching image-enhanced documents
• Accessing graphics -intensive files
• Conducting unified voice/data messaging and Internet telephony
activities
Stackable switch technology offers a solution for im proving network
performance, relieving bandwidth bottlenecks, while allowing small
offices to preserve their investment in their current network
infrastructure. Stackable switch technology also offers advantages in
performance and provides the framework for utilizing evolving
technologies, such as Gigabit Ethernet, as they become available.
This White Paper explains stackable switching technology, its origins,
and its advantages. This Paper also identifies the features to look for
in a stackable switch.
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The History of Stackables
Historically, the stackable concept has been the preferred method of moving data between different nodes and
devices on larger networks (more than 20 users). First introduced in network hubs, the stacking solution proved
immediately successful for many reasons, particularly those of flexibility and price.
With the advent of the network switch, the stackable concept became
popular once again. Unlike hubs, which are designed to share the
available bandwidth through port bandwidth degradation, a stackable
switch provides full bandwidth to each of the ports on the switch. For
example, a heavy-traffic hub with 16 10/100 ports might forward as
little as 6.25 Mbps per port, while a full-duplex switch can move close
to 200 Mbps of data on each port.
What is a Stackable Switch?
Stackable switches are single -configuration switches that can be stacked
and interconnected through proprietary ports. The concept of stacking,
however, is more than just physically placing one switch on top of
another or connecting some switches using a proprietary connection.
The essence of stacking starts with bandwidth. In a stacking
arrangement, the connection between any two switches must provide
future-proof bandwidth to prevent oversubscription as additional
switches are added. For this reason, stackable switches that have a
high-performance, high-availability uplink port can create a fat -pipe
connection between cascaded switches that boosts the backbone bandwidth,
eliminating backbone bottlenecks and net work-looping issues.
A stackable solution should also free users from the yoke of having to
choose between performance and price. Unlike chassis -based solutions,
which require a significant initial investment of the physical chassis,
truly stackable solutions should allow users to buy only the number of
ports required at the time of purchase, with the ability to upgrade to
additional ports at a later date. (This advantage was one of the key
reasons contributing to the popularity of stackable network hubs.)
Additional benefits derived from a scalable stacking technology include:
• Seamless migration from 10 Mbps to 100 Mbps to 1000 Mbps (1 Gbps).
• Easy expansion to match an organization’s future networking
requirements. For example, you can readily expand network size (number
of nodes), and performance (bandwidth) in incremental steps, maintaining
interoperability throughout.
• The flexibility to redeploy network resources if and when the need
arises. Scalable stacking technology also makes it easy to add s witches
to support more users, thereby providing greater bandwidth and
protecting against network downtime. In this way, small office can
respond to business changes while obtaining peak performance from
existing infrastructure.
The Challenges of Network Growth
In assessing your own need for scalable solutions, consider the
potential impact of the following industry-wide trends on your network.
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Trend mpact
Deploying highperformance PCs as
clients and servers
Increasing reliance
on client/server
solutions
The avalanche of IP
traffic
Dramatic rise in
backbone traffic
Today's Pentium III-based clients and servers can place
significant amounts of information on the network.
More and more applications are being installed on servers
rather than on desktop PCs, greatly increasing the amount of
traffic on the network. At the same time, the applications
themselves are requiring greater bandwidth. This trend will
accelerate as small offices increase their reliance on
resource -intensive applications such as distributed data
bases, e-mail supporting multimedia atta chments, CAD, audio
and video transmissions, groupware and push technologies.
The increasing dependency on the Internet and intranets as
business tools means that large files are uploaded and
downloaded frequently over the netw ork. In fact, the
widespread popularity with the Internet and Web browser based applications has made IP the primary protocol on the
small -business intranet.
In the past, data traffic flow within the workplace followed
the “80/20 rule," which held that 80% of network traffic
stayed within the workgroup and only 20% was traffic to and
from the server. In a recent survey, Dataquest, a marketresearch firm in San Jose, CA, found that the deployment of
applications on the server, coupled with the increasing use
of intranets and the Internet, has inverted the 80/20 rule,
with 80% of the network traffic making it to the server and
only 20% remaining local.
Architectural shifts
Consolidating
networks
The trend of deploying “thin clients” ? desktop devices
equipped with a minimum of computing power ? places an
additional strain on network capacities. Thin clients need
to contact the server continuously, not only to download the
initial applications, but also for applets that change fonts
or create tables.
As older technologies are phased out within an organization
and those legacy users migrate to Ethernet, the number of
people sharing Ethernet bandwidth increases.
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The Expense of Network Downtime and Lag Time
As a small bus iness increases its dependency on the network, its
employees ? and its customers ? become less tolerant of LAN downtime
and sluggish response times. At a small business that sells musical CDs,
for example, operators taking telephone orders typically interact with
the corporate database and with the database of an outside credit-card
company. When demand on the system is high (just after a radio
advertisement is aired or following a catalog mailing, for instance),
response time slows. A delay of a second or two is irritating, but a
delay of 15 seconds or more means the small business risks losing the
sale and the customer. This example illustrates how the network plays an
integral role of how a small company conducts business. Not many
companies can live with out it.
In fact, a survey conducted by the International Data Corp., a marketresearch firm in Framingham, MA., found that nearly 75% of managers
consider their networks to be critical to their company's operations.
Moreover, network downtime can be exceedingly expensive. In fact, by
some accounts, network downtime results in financial losses that cost
companies hundreds or even thousands of dollars per hour.
Clearly, small offices have to provide more capacity and higher
reliability to their networks. But because the networks have become
critical to the company, managers can't just yank everything out and
start over (much as they might like to). Hence, the window of
opportunity for scalable stacking technology.
Features to Look for in a Stackable Switch
Stackable switches offer a variety of features that may affect their
suitability in a small business environment. The following sections
describe some of the key features to consider before making a switch
purchase decision.
Backplane Speed
Traffic between switches travels along a high-speed backplane.
Therefore, it is important to use stackable switches that employ fast
backplane speeds to maintain the highest performance to the desktop ?
especially as the network grows.
Load Balancing
Load balancing refers to a switch’s ability to distribute network
traffic evenly and intelligently across the backbone that exists between
two switches. In this way, load balancing ensures that traffic is
distributed efficiently and effectively across the stacking connect ions.
Fault Tolerance and Redundancy
Fault tolerance and redundancy are important switch functions. With
these features, the failure of one link causes the switch to
automatically reroute packets to one of the remaining operational links,
usually without users noticing the exchange. In this way, fault
tolerance and redundancy ensure network integrity and avoid network
segregation if a link goes down. The switch you select should also
support “intelligent” fault-recovery capabilities, which allow it to
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start passing data through the failed port once that port becomes
operational.
Reliability
Access to information is critical to any company’s success. A switch’s
reliability, therefore, offers companies the security of network uptime
along with the timely delivery of information.
Ease of Installation and Maintenance
Faced with the challenges of creating and maintaining a reliable, high performance network infrastructure with limited personnel and budget,
small offices require equipment that is easy to install, manage, and
maintain; cost-effective; scalable; and dependable. Choosing a stackable
switch that offers ease of use and set up, therefore, should allow any
level IT personnel to install and configure the switch.
Seamless Integration
Another important feature to look for in a switch is its ability to
integrate new technology seamlessly. A well -designed switch allows small
offices to adapt easily as their computing needs change and new
technologies emerge.
Conclusion
Implementing a stackable switching sy stem can help small offices migrate
from shared to switched networks while maintaining current performance,
protecting existing infrastructure investments, and establishing a
foundation ready for future network.
Stackable switches offer an attractive way to relieve bandwidth
bottlenecks and provide faster response times for networked PC users. A
quick and cost -effective solution, stackable switches are also easy to
deploy in an existing or new network environment. Installation is simply
a matter of plugging the switch in and attaching devices to its ports.
Bandwidth problems are promptly resolved without wiring changes or any
upgrading of individual desktop PCs. This ease of configuration is
comparable to hubs, making stackable switches an appealing choice
especially for companies with small LANs.
With new switches designed specifically for connecting devices and
desktops, small offices no longer have to invest in expensive and
inflexible switches engineered primarily for larger workgroup
environments and backbone implementations. Instead, they can deploy
scalable, affordable switches that increase the aggregate bandwidth of
the network by boosting throughput to the workgroups that need it most.
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