Home > Articles > Networking > Wireless/High Speed/Optical

Cisco 802.11 Wireless Networking: Installing and Configuring Access Points

The largest hurdle toward getting your wireless LAN (WLAN) up and running is the configuration of your access points (APs) and wireless clients. This chapter examines how to install and configure the AP.
This chapter is from the book

The largest hurdle toward getting your wireless LAN (WLAN) up and running is the configuration of your access points (APs) and wireless clients. The next two chapters examine how you can install and configure both devices. First, let's consider the AP.

Site Survey

Before you install or configure an AP, you should first conduct a site survey. This exercise shows you where the best—and worst—places are in your organization for Wi-Fi reception.

You use an AP and a client to conduct a site survey. Both the AP and client move around to various, temporary locations in an effort to find ideal placement.

Once completed, a thorough site survey tells you:

  • Coverage of APs and the ideal location of APs in your WLAN.
  • Bit rates and error rates in different locations.
  • Whether the number of APs you plan to deploy is enough.
  • The performance of applications on the WLAN.

AP Location for Site Survey

When you perform a site survey, try to situate the AP as close to its ultimate location as possible. This helps resolve any problems that might creep up after you mount the AP.

In most cases, you should mount APs at ceiling height. In warehouses and other sites with high ceilings, it's best to mount them between 15 and 25 feet. If you mount them at this height, power delivered to the devices must be addressed. Power over Ethernet (PoE) is discussed in greater detail later, but this is an excellent scenario where you should deliver power in via a power injector, line-power enabled devices (such as Catalyst switches), or line-power patch panels (sometimes referred to as a mid-span device). PoE can save a lot of headache and expense.

In some environments it might be desirable to keep the AP out of sight. If you opt to place the AP above ceiling panels, you should place antennas below the ceiling for optimal reception. If this is the case, you should purchase an AP that fits for remote antenna capability.

Performing the Survey

There are two ways you can perform a site survey: manually or assisted. You typically use the manual method when you first install a WLAN.

If you already have a WLAN in place and just want to tweak it, an assisted site survey saves you a lot of shoe leather.

Manual Site Survey

The first way to conduct a site survey is called a manual site survey. This means you pick up a Wi-Fi-enabled laptop, palmtop, or specialized wireless survey device and walk around your site and record data from the temporarily located AP as you go.

You should place the AP and antennas where you decide to mount them. However, before you actually mount them, perform the survey, and take your Wi-Fi-enabled device to various client locations within its coverage area.

Cisco wireless client adapters (which are examined in greater detail in Chapter 6, "Configuring Clients") include the Cisco Aironet Desktop Utility, which includes a site survey tool component. This tool allows you to view the strength of your AP's signal, the quality of the signal, packet retries, and a host of other data. This tool is shown in Figure 5-1.

05fig01.jpg

Figure 5-1 Aironet Desktop Utility Site Survey Tool

When you conduct a site survey, be aware of these issues:

  • Wood floors can cause floor-to-floor interaction between APs. Think three dimensionally. Make sure channel selections are appropriate for APs located on adjacent floors.
  • Office and room doors should be closed before beginning the survey. This shows how the WLAN performs in real, day-to-day functioning.
  • Metal blinds should be closed because, in this position, they are major disruptors of signal quality.

Follow these steps when you perform a manual site survey:

  1. Start with a building map or layout that shows all the coverage areas.
  2. Identify and record possible sources of interference, including elevators, microwave ovens, HVAC units, power distribution closets, and so forth. Metal bookshelves and cabinets can also disrupt your AP's signal.
  3. Move around your facility, and make note of signal strength, signal-to-noise ratio (SNR), and packet retry counts.
  4. Move the AP to a different location and with a fresh copy of the facility schematic, repeat step 3.

It's easy to look at the signal strength meter on your site survey tool and make assumptions based on the strength of the signal you receive. However, you should also be cognizant of the signal-to-noise ratio (SNR). If noise in the band is too high, it can cause reception problems—even if you have a strong signal from the AP. Use the SNR and packet retry count (the number of times packets were retransmitted for successful reception) to get an accurate view of your signal quality.

Packet retry count should be below 10 percent in all areas. You should use packet retry in tandem with the SNR reading for a good picture of signal quality. The signal might be strong enough, but because of noise or multipath interference, packets are resent. Without an SNR reading, you cannot tell if packet retries spike because you are out of range, there's too much noise, or the signal is too low.

Assisted Site Survey

If you use the CiscoWorks Wireless LAN Solution Engine (WLSE) or a Wireless LAN Controller, you can perform an assisted site survey. This survey allows you to simulate the optimal radio transmit power and channel selection in an existing WLAN. You can select specific APs in your WLAN, and then generate your results. The assisted site survey allows you to:

  • Select specific APs to test
  • Perform a radio scan
  • Perform a client walkabout (not performed on the WLAN Controller)
  • Generate radio parameters

The benefit of this test is that it allows you to conduct the site survey without the need to walk all over your office (unless you chose the client walkabout test, of course). It also allows you a certain level of granularity, to pick and choose which devices to test. Although this tool is great for WLANs with existing APs, it's not ideal for preinstallation work.

We discuss CiscoWorks WLSE in greater detail in Chapter 10, "CiscoWorks Wireless LAN Solution Engine (WLSE)."

Analyzing Your Site

After you conduct your site survey, it's time to analyze the data. If you conduct a manual site survey, bring a map along with you and record site data for each location. After you complete the survey, sit down and examine the map. Do you notice poor signal reception in certain areas? What characteristics are at play in that area that might affect signal quality?

You should also experiment with different AP and antenna locations to find the best site. Use different maps for different AP placement options, as this helps you keep your data clear and easy to understand.

If you encounter interference you simply cannot locate, you might need to use a spectrum analyzer. These devices scan a wide frequency band to locate transmissions. Unfortunately, they are also expensive. You can expect to pay thousands of dollars for one (or you can rent one). On top of the expense, there's a steep learning curve in their configuration, setup, and use. If the purchase of a spectrum analyzer is not in your budget, you might hire a consultant with specialized tools to conduct the site survey.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020