The push to implement wireless networks almost always comes from outside of IT, from users such as roving meeting attendees, presenters, and even employees who like to sit outside and work at the picnic table. If you've so far resisted such pressures, I have good news for you: Today's hardware is easier to implement, faster, and more secure than hardware a year or two ago. In fact, in just seven relatively easy steps, you can implement a secure wireless network in your environment.
Step 1: Verify the Business Need
Although you might think your company is ready to deploy a wireless network,
you still need to weigh the pros and cons of such a deployment and determine
whether it will suit the needs of your business. A wireless network can be less
expensive to deploy than a wired network in areas in which physical cabling
is difficult to install and prohibitively expensive. Your users have probably
argued other benefits of deploying a wireless network, including better productivity
through connectivity in meeting areas and campus environments. Still, it's usually
wise to subject those expectations and claims to a reality check. When you can
verify the need for truly mobile users to maintain network connectivity, you'll
be able to make a business case for a wireless network.
Wireless networks also have some disadvantages, including shared-bandwidth
and security concerns. Depending on your users' expectations and experience
with wired networks, available bandwidth might not be a big concern. You also
need to be aware that a wireless radio in an Access Point (AP) has a maximum
throughput, which all users who simultaneously connect through that radio must
share. And, of course, network traffic carried on a wireless signal that's broadcast
into the open air will be more susceptible to interception than is traffic over
a physical cable inside your office, although new standards keep wireless transmissions
more secure than they've been in the past. I discuss these standards in depth
later.
Step 2: Determine Your Coverage Area
After you decide that your business really does need a wireless network, you
have to determine which areas will require wireless coverage. Your wireless
coverage should be driven by the business needs that you discovered in the first
step. I highly recommend plotting a rough layout of your ideal wireless network
on a diagram of your building or campus that's drawn to scale. When you're planning
maximum coverage areas, you can use a 300-foot radius as a general rule of thumb,
but keep in mind that as the distance between a client and an AP increases,
the data rate and signal strength decrease.
When you've determined where you need wireless coverage and created a rough
map of where you want to place your APs, you'll need to make sure those locations
are suitable. APs require power and wired network connections. If power is a
problem, you'll need to buy APs that use Power over Ethernet (PoE), which I
discuss later.
Step 3: Plan Bandwidth Utilization
If you'll be offering wireless connectivity to a large group of users or to
a bandwidth-hungry user group, you might want to consider increasing the number
of APs to provide more throughput per user. For example, four users who are
connected to one 802.11g AP and are communicating on the same channel would
theoretically share 54Mbps of bandwidth, giving each user a quarter of the available
bandwidth, or 13.5Mbps. (Step 4 explains the relationship between throughput
and the number of channels.) Adding a second AP would give each user a maximum
throughput of 27Mbps. (Both APs would require load-balancing capabilities to
ensure that bandwidth is distributed equally among the users.)
Step 4: Make Your Hardware Requirements List
Now that you've prepared for a wireless LAN (WLAN) implementation, you have
a few hardware components to consider. You'll need APs and wireless adapters,
as well as a wireless bridge, specialized antennae, or wireless switch, if needed.
APs are the transmitters and receivers that communicate with wireless devices
and provide a communication path to the wired network. Wireless adapters, which
you install in client systems, let clients communicate with the wireless network
just as a traditional NIC lets them access the wired network. A wireless bridge
connects two network segments wirelessly, which can be handy if you need to
span difficult-to-wire areas, such as between buildings. Specialized antennae
can provide an extended or tighter coverage range. For example, if your company
needs a point-to-point wireless network between buildings, you might use a Yagi
antenna to focus the wireless radio signal and aim it at the opposite AP. If
you want to enable centralized management of your APs, you also might want to
deploy a wireless switch in conjunction with compatible APs. Vendors offer this
combination of hardware to let you control access, maintain security configurations,
monitor usage, detect rogue APs, and provide seamless roaming from a central
management point.
By now you should have a good idea of how many APs, wireless adapters, and bridges you'll need. You also should have a short list of features that you want your hardware to support, such as PoE and load balancing. Although most enterprise-level wireless network gear offers the latest in security features, you'll also want to include any security must-haves on your hardware requirements list.
If you're deploying a wireless network from the ground up, one of the most
important decisions you need to make is which wireless standard to follow. There's
some level of interoperability between standards (Wi-Fi certified equipment
provides the best cross compatibility), but you'll be best served by adhering
to a single standard. The 802.11a and 802.11g standards boast 54Mbps speeds,
and the original 802.11b standard provides a data rate of 11Mbps. Although you'll
see 802.11g equipment that claims speeds as fast as 108Mbps, it can achieve
those speeds only through hardware data compression, and as with all compression
technologies, the compression ratio depends on the data being compressed. If
you don't need the speed, 802.11b equipment is quite inexpensive, but be wary
of early-generation equipment, which might lack some of the security capabilities
I discuss later. Most companies choose either 802.11a or 802.11g. Table
1 compares the characteristics of the wireless standards that you should
consider when making your decision.
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