Going Wi-Fi: A Practical Guide to Planning and Building an 802.11 Network

In the decision-making process, management and IT analysts need to evaluate the WLAN technology alternatives from the perspective of their organizations' short-term and long-term communication objectives. Here's a suggested check list to use during the evaluation process:

• Number of concurrent users-how many people do you expect to access the WLAN on a daily basis? What percentage of that group is expected to be accessing the WLAN at any one time?

• Number of stations-this refers to the total number of computing devices, wireless printers, perimeter surveillance systems, and so forth that is expected to be used to access the WLAN.

• Type of use-to provide wireless Internet access to the public, to support distribution center activities only, to enable visitors to access the network with ease, or perhaps to enable widespread use of wireless connectivity.

• Short-term and long-term objectives for the WLAN.

• If the wireless technology is to be deployed to support a business or home network, what applications-email, instant messaging, word processing, PowerPoint presentations, instant sharing of design schematics, video streaming-will regularly traverse the WLAN system?

• If the WLAN isn't to serve a HotSpot-determine the type of computing devices (e.g. laptops, PDAs, printers) that will access the WLAN. If certain end-users will use the WLAN to access data-rich applications and Internet content, including streaming audio and video, laptops are a better choice for those users than a smaller PDA or other type of handheld computing device.

• Expandability-is the WLAN deployment designed for only a small group of end-users and if so, are there plans to expand the WLAN in order to bring wireless connectivity to others in the future?

• Software and hardware-if the network will be built with gear from various vendors, stage a trial run to ensure compatibility.

• Vendor support-what do they offer? As with any technology, good vendor support is crucial.

• Mobility and flexibility-what degree of mobility will the end-users require? Moving about within a single building, from building to building, throughout a large campus or what? Will all of the end-users be using the same type of computing device (e.g. all using laptops or will some be using PDAs or vice versa)? For instance, a HotSpot must be designed to support a variety of devices, but a corporate WLAN also may be expected to support a mix of computing devices. In that case, you need to determine if the mix is throughout the organization or only within groups (e.g. only warehouse personnel will be using handheld computers, everyone else will be using laptops)?

• Environment-will the WLAN provide wireless connectivity to a warehouse, office space, medical facilities, manufacturing plant, campus, or some mixture of these?

• Maintenance-how will the WLAN be maintained so that end-users won't suffer from dropped signals or interference?

• Life cycle-are you building the WLAN to accommodate end-users while attending a conference, or a training session, or are you building the WLAN as part of the organization's permanent network infrastructure?

• Speed-applications and number of concurrent users-bandwidth intensive applications will be intolerant of speed fall backs due to interference, distance or heavy user activity.

• Range-here you need to be specific about how far the signal should reach, if only for security purposes.

• Frequency-there are some differences between 11a, which uses the 5 GHz frequencies, and 11b and 11g, which use the 2.4 GHz band.

• Equipment connectivity-a clear line of sight is important for quality connectivity, but also consider network equipment placement insofar as electrical power and cabling are concerned.

• Manageability-this mainly refers to training the IT department in the complexities of managing a WLAN. But you also need to consider the overall WLAN architecture in light of possible manageability problems that could crop up or could be avoided with more attention to design details.

• Security-there are many other aspects of securing a WLAN such as availability, survivability, intrusion detection, and user privacy. Even with the 802.11's flaws, it is still possible to secure a WLAN to an acceptable level by following a few basic principles.

• Connectivity with other wired and wireless networks-is there a wired network that will be accessed via the WLAN? If so, is its technology compatible, i.e. all Ethernet, all Token Ring? Are there any other wireless networks in operation? If so, are they compatible with the proposed WLAN?

• Location-this refers to the country where the WLAN is in operation. Does it meet that country's regulatory conditions? For example, are the antennae in compliance with FCC regulations?

Filling in the "blanks" for each of these items puts you in a much better position to make the right technology choices. Use the information in Chapters 7 and 10 where we examine the different characteristics of 802.11a, b and g. This includes the particular networking environment issues relevant to making a decision as to the make-up of a wireless network's architecture compared to the technology to be used.

Read Section VII: The Hardware for an in-depth discussion of the wireless networking gear available for deploying a wireless network. Only the WLAN deployment team will know which components (including their various permutations) are necessary to enable the end-users to obtain an optimal wireless networking experience.