7 Steps SMBs Need To Know For Choosing a Local Area Network ...
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7 Steps SMBs Need To Know For Choosing a Local Area Network Switch
By Barbara Finer, 3Com, Director of SMB Marketing
The Truth about Networking
Network technology, and in particular, the network switch, are essential to running an efficient,
competitive, cost-effective business. They let your business instantly connect employees,
customers, suppliers and other partners to current information. They allow your organization to
collaborate using a range of media—voice, data, and video—to share knowledge and coordinate
projects, leading to greater productivity and customer satisfaction. They help your business be
more efficient, have workforce flexibility, perform professionally 24/7 and grow.
Why Do You Need a Network Switch?
A fundamental component of any business network, a switch allows users to communicate and
share information with each other over a local area network (LAN). LANs connect the people and
devices in a local geography such as an office, department or building.
LANs today are based on Ethernet (referred to as IEEE 802.3), a widely adopted standard for
wiring, signaling and addressing. Every device on the LAN has a unique address, just like your
business does. An Ethernet LAN readily connects a variety of products, including wireless fidelity
(Wi-Fi) devic es and Voice over Internet Protocol (VoIP) devices such as IP phones. These
connections involve a variety of speeds, signals and/or cables, and are made possible by a
The switch uses its physical connection points (ports) and software intelligence to transmit
information as “data packets” between client devices, including PCs, printers, IP cameras, IP
phones and LAN devices such as servers, wireless access points, other switches and routers.
Data packets actually carry digital voice, video or data.
The switch inspects the packets as it receives them. It determines the source and destination of
each packet, sets up the best network path to get it to its port or destination, and forwards it
appropriately. Speed and coordination are essential, otherwise the packets collide or get
Some switches can be configured and managed so that certain traffic is segmented—transmitted
only through specific ports for performance or security reasons. Packets from a payroll
application, for instance, should be segmented to pass only through ports that connect the
authorized users in Finance or Human Resources. And because packets from voice applications
are latency-sensitive (delays cause the data to decompose; voice “breaks up”), they should be
partitioned and prioritized over other applications.
The switch receives and sends packet traffic outside the LAN through a router or gateway. This
edge device connects the LAN to external wide area networks (WANs) such as the Internet, using
a broadband service (such as public DSL or cable, or private T1 or E1).
Now that you know “why” a switch, how can you decide what is the best one for your business?
How to Select a Switch: 7 Decision Factors
1. Number of Ports
This is a function of the number of devices to be connected. Here is an easy way to identify how
many switch ports you need:
• Count the number of user devices to be physically connected (by cables) on your LAN. Include
PCs, laptops, printers, scanners, fax machines, IP video surveillance cameras and IP phones,
etc. Remember to include those in conference rooms, reception areas, stock rooms or
warehouses. Do not count wireless user devices; they connect to your LAN through a wireless
access point, a network device that is included in the next bullet.
• Count the number of network devices to be physically connected on your LAN. Include routers,
servers, wireless access points (each of which typically supports 20 or more wireless users), IP-
PBXs and security devices such as firewalls, etc.
• Add ports to accommodate the growth that you anticipate in user and network devices within a
few years. The sum of these numbers is the minimum number of switch ports you need; a rubric
often used by technical experts is that the number of ports should be about 15% greater, to
accommodate unforeseen needs. 3Com switches range from just a few ports to dozens of ports.
Switches can often be connected to each another to multiply the number of available ports, and
some higher-end switches can be “stacked” (combined to operate as a single entity, as if all their
ports are in one very large switch).
2. Network Speed
Speed is sometimes referred to as “bandwidth”, which is the amount of digital data that can pass
through a network connection in one second. Speed is measured in megabits (millions of bits) per
Although the LAN connection capability in newer computers transfers data packets at close to
1000 Mbps (one Gigabit per second), many business LANs still transfer packet traffic at 10 Mbps
or 100 Mbps.
A “10/100” LAN (which uses the 10BASE-T and 100BASE-TX Ethernet standards) supports both
10 Mbps and 100 Mbps (“Fast Ethernet” or “FE”) speeds; the switch port matches the speed of
the device connected to it. 10/100 LANs most often use twisted-pair (copper) cable, which allows
the physical connection (between a switch and device) to be up to 100 meters long. Some 10/100
LANs also use fiber-optic cable, which allows connection lengths up to 2 kilometers.
Although 10 Mbps technology is over 25 years old, and 100 Mbps is over 10 years old, 10/100
LANs are fine for most data applications and many web and graphics applications. Most
computers have a built-in Ethernet interface, a network interface card (NIC), for network
connections. The NIC provides a unique media access control (MAC) address that enables the
computer to send and receive data packets. In computers made prior to 2006, this interface
typically supports data transfers at 10 Mbps or 100 Mbps.
A Gigabit Ethernet LAN switch (which uses 1000BASE-T and/or 1000BASE-X standards)
actually supports all three speeds—10/100/1000 Mbps—making it an ideal solution for computers
of various ages. A business with a Gigabit LAN can use twisted-pair cable, which allows physical
connections up to 100 meters long, or fiber-optic cable (1000BASE-X), which allows higher
quality data signals, greater speed and longer connection lengths. A switch that is equipped with
a small form-factor plugable (SFP) optical transceiver can connect to either twisted-pair or fiber-
optic cabling; this lets the SMB select the appropriate cabling for each link.
Gigabit connectivity is important for applications that use video, voice or complex digital images
(including Web 2.0 applications). LAN ports that can deliver Gigabit speed are also best for
connecting wireless devices that use the new high-performance IEEE 802.11n standard, because
its data rate exceeds 100 Mbps.
The 3Com SMB switching portfolio offers extensive Gigabit and 10/100 port options. 3Com also
offers enterprise-class switches with 10 Gigabit ports for larger networks and especially
demanding applications such as video broadcasting, digital imaging, real-time financial
transactions, large database access and data backup.
3. Switch Management
This option determines the level of control you can have over your network, including the degree
of security that your business wants for its networked data and communications. Managed
switches offer more control; they also usually require more technical expertise. A network can be
a mixture of managed and unmanaged switches.
Unmanaged switches are preconfigured entirely by the manufacturer based on industry-
standard best practices for security and performance. This makes setup quick and easy, and
reduces the price. You cannot use an unmanaged switch to segment one group from another or
give priority to certain users; however, many 3Com unmanaged switches have a feature—support
of the IEEE 802.1p standard—that can prioritize voice or video traffic higher than data traffic.
Unmanaged switches are appropriate for many businesses. They satisfy most small business
needs and can be quickly set up.
Managed switches provide control capabilities that can increase LAN security and performance,
and let you segment traffic. For example, you could allow only certain employees to have access
to your financial applications. You could also give some applications more bandwidth, or ensure
that video and voice communications take priority over data.
Managed switches are typically required—for performance or security reasons—for business-
critical applications such as Customer Relationship Management (CRM), Sales Force Automation
(SFA), video surveillance, digital medical images and regulatory compliance, as well as for real-
time applications such as audio/video streaming, distance learning, sales demos and VoIP. Many
businesses that have multiple switches prefer the managed versions because they can configure
them for consistency.
Some managed switches are “plug and play”, meaning that they work out of the box using the
manufacturer’s configuration, without any need for technical expertise. You, your value-added
reseller (VAR) or IT consultant can implement more of the switch’s management capabilities later,
as needed. Managing a switch beyond its plug-and-play settings requires some technical
expertise, which can be obtained through the user guide, training, or a VAR.
You have several options in user-interface formats for switch management. Most SMBs prefer
management that is “centralized” (vs. local) because it eliminates the need to physically travel to
a switch to adjust, monitor or restart (reboot) it. IT staff can manage the switch remotely, using a
number of user interfaces. Centralized management is available in these formats:
• Smart web-managed. This simplified format requires little or no expertise. It provides a select
set of management features (such as configuration of port speed and traffic prioritization) for a
price much lower than a fully managed switch. 3Com smart web-managed switches are plug and
play; they also can be easily configured and operated without any need for a lot of technical
expertise, using the built-in online help for each of the features. Web-managed switches are
configured through a browser instead of a desktop utility; managing over the web can be secured
by using HTTPS.
• Command-line interface (CLI) management. This type of management is convenient for quick
set up and configuration, and provides more control than the web-managed format. It also
requires more technical expertise.
• SNMP management. The Simple Network Management Protocol format offers the highest
degree of control and the most comprehensive management, including automatic monitoring,
reporting and correlation. It requires the most technical expertise. It is the basis of most network
management applications software.
Do You Need Management?
If you want any of the following technical capabilities, your business does need a managed
• Turning a port on or off, or enabling and disabling a port’s fullduplex mode (simultaneous two-
way data transfer for greater speed) to control port security or performance.
• Securing access to your LAN, switch, and/or transmissions over the web.
• Prioritizing applications traffic, for example, by using Differentiated Services (DiffServ and
DSCP) or IEEE 802.1p to provide Quality of Service (QoS) for voice or video packets.
• Creating a IEEE 802.1Q VLAN to place users who are on different LAN segments or in different
locations on the same LAN, and/or to increase security and performance.
• Using Auto VLANs to automatically place authenticated users into a specific VLAN, controlling
their access to data and/or the performance of their application transmissions. (Some 3Com
switches include auto-voice VLANs; see Decision Factor 5, Voice-Ready).
• Increasing bandwidth and network availability by using IGMP snooping, the Spanning Tree
Protocol, Rapid Spanning Tree Protocol (RSTP) or Multiple Spanning Tree protocol (MSTP); or
Link aggregation (either manually or automatically with LACP).
• Using SNMP to monitor device connections and performance for the purpose of tracking and
reporting, diagnostics or regulatory compliance.
A Brief Tutorial On Layer 2/3/4 Switching, Or L2/L3/L4
Switching and switch management occur at several layers of the OSI Model (Open Systems
Interconnection Reference Model) and TCP/IP Model(Transmission Control Protocol/Internet
Protocol Model). Both models are abstract network architecture standards for computer and
The OSI model defines seven major functions, or layers, needed for network communications.
Identifying a switch by its OSI layer helps explain the functions that the switch is capable of
Layer 2 switches keep it simple: they look only at MAC addresses when deciding where to
forward packets. Layer 2 switches tend to be the least expensive and good for local workgroup
switching. However, they cannot forward traffic across VLANs or to external networks such as
the Internet; they have to send this traffic through a router or Layer 3 switch.
Layer 3 switches also look at IP addresses. Forwarding based on Layer 3 is called routing (Layer
3 switches are also known as switch/routers). They are good when traffic must be forwarded
across VLANs. Layer 3 switches can increase LAN performance by offloading some of a router’s
Layer 4 switches also look at applications when deciding where to forward packets. They are
good for prioritizing applications traffic such as VoIP, video streaming, Lotus Notes or Microsoft
4. POWER OVER ETHERNET
With this option, a switch port provides electrical power through the Ethernet cable to the
attached device. Industry standard (IEEE 802.3af) PoE ports eliminate the need to install (“run”)
and operate separate electrical and network wiring: the inline power from a PoE switch port
allows a PoE-compatible device to be placed anywhere there is a twisted-pair Ethernet cable
(CAT5 or better). PoE switch ports are especially useful for connecting devices such as wireless
access points, IP security cameras and IP phones.
PoE technology provides three major benefits:
• Flexibility. PoE increases the placement options for devices. For example, you can place a
wireless access point up high on a wall or on the ceiling to get optimum RF coverage. All you
need is one Ethernet cable, there’s no need for another power source.
• Cost savings and time savings. You save the labor and materials costs—and delay—that
otherwise would be incurred to have an electrician run more electrical wiring and install outlets.
The lower voltage of PoE means that the twisted-pair Ethernet cabling can safely be installed in
many locations by anyone. For example, you could quickly place and connect a video
surveillance camera yourself.
• Non-Stop business. Devices (such as wireless access points, IP phones and IP cameras) that
are connected to the switch’s PoE ports can continue operating after a power failure if you have
provided your PoE switch with redundant power circuits connected to an uninterruptible power
supply. Different devices draw different amounts of power. IEEE 802.3af PoE switches offer a
range of internal power supplies and number of PoE ports that let them support a variety of
device power requirements and peak usage loads, up to 15.4 watts per port.
5. Voice-ready Switching
By choosing a voice-ready switch, your business can run voice traffic over your LAN, and replace
a traditional PBX or other telecommunications service, now or in the future.
With an IP telephony system and IP phones (wired or wireless phones that act like specialized
computers), you can combine or “converge” your data and voice services into one secure digital
network that interoperates with the public telephone system (PSTN) or a contracted VoIP service.
The benefits of doing this are cost savings, greater user and IT staff productivity, and
improvements in customer service and sales. For example, convergence can reduce toll call
charges and conferencing service charges, unify voicemail and email messaging, and allow a
phone to be moved to another location or port and retain the same extension, owner recognition
and settings. A business can also take advantage of communications applications such
interactive voice response (IVR) and autodialing customers or employees from a database.
Because voice traffic is delay-sensitive (“low latency”), the network switch must have technology
features that make it voice-ready. All 3Com switches that are voice-ready include:
• IEEE 802.1p QoS, which expedites and filters traffic. This standard allows the switch to reorder
packets based on their priority value so that voice calls get adequate bandwidth to ensure voice
Some 3Com voice-ready switches also include these voice support features:
• DiffServ, DSCP and IEEE 802.1Q VLANs, which help to process voice and video traffic
• Auto-voice VLAN, which automatically detects and connects any standards-based IP phones
and assigns VoIP traffic to a voice dedicated VLAN with appropriate QoS. This advanced feature
optimizes delay-sensitive traffic
6. Form Factor
Your choice of switch format depends on the layout of your work environment, your desire for
quiet operation or physical security, and the number of switch ports you require. (Note: the
following are the design differentiators, but both formats may be placed on a desk or in a rack.)
Desktop switches are designed to sit atop a desk or table. They are often the choice for
conference rooms and smaller offices. They are generally smaller and quieter with a lower
port count and cost than other switches.
Rack-mount switches are designed to be placed in a rack that is located in a wiring closet or
other enclosed, physically secured room that typically houses other network devices, such as
servers and telephony equipment. Rack-mount switches are often the choice of small and
midsize businesses, as well as larger enterprises. Rack-mount switches often have fans,
mounting brackets and a higher port count.
7. Requirements of Your Business
It may be last in the list, but this decision factor is certainly the most important when choosing a
switch or other network equipment. You are the one who knows which of these product
requirements are priorities for your business:
• Easy to set up and use, whether wired or wireless.
• Secured against external and internal vulnerabilities.
• Affordable without reducing quality.
• Simple to integrate into your business.
• High performance, whether with data, voice or video applications.
• Reliable and backed by strong warranties and service.
• Flexible and based on open standards, so you can take advantage of valuable new business