Deploying the WLAN


Deploying your WLAN will likely be a complex process-driven effort. It will require careful project management and scheduling to ensure smooth transitions between each set of tasks. In this, it is not unlike any other technology implementation once the architecture and design have been defined.

There are usually multiple groups or teams involved in a WLAN deployment. These will include your core IT wireless team, your cabling vendor, the group responsible for workplace resources (power, occupational health and safety, office management, and so on), your technical support organization, network operations staff, and any external vendors you select to assist in the deployment. Large enterprises will most likely also have a program management team to oversee the multiple installations and sites, manage the multiple projects, report to the stakeholders, and controls costs. Although the program management team may not be considered an integral part of the deployment per se, it will likely be involved in the day-to-day implementation.

Figure 6-2 shows the relationships among groups involved in a typical deployment. It is important to carefully manage these relationships and ensure that good project management techniques are used to avoid unnecessary delays or problems.

Figure 6-2. Possible Deployment Teams and Their Relationships


The following section describes some of the key tasks and activities required during the deployment phase.

Pre-Deployment Tasks

At this stage, you should have decided whether to use external vendors to assist in the deployment. If you have chosen to use external vendors, ensure that they are familiar with your existing network infrastructure, the scope of deployment, the locations of each site, and the fundamentals of your wireless architecture. Some time spent on transferring information to your vendor will help avoid later confusion and delays.

Independent of retaining outside help, you should have a detailed project plan and implementation schedule in place. The relevant IT resources should be assigned, and the team should be familiar with the architecture. It is possible that a pilot network will have been undertaken to validate your architectural decisions, familiarize your IT staff with the technology, and test the solution. Indeed, for larger deployments, a pilot is highly recommended.

A communication plan should by now have been undertaken, and your end users should be aware of the upcoming technology, your security standards and wireless policies, when they can expect to receive their client hardware (if necessary), and when the service will be launched at their site.

Managing the Deployment

The actual deployment of the WLAN will most likely follow a number of common steps for each site. The makeup of the teams involved will depend upon your choice of IT staff, the use of internal staff or external vendors, and whether local resources are available. Each set of tasks should be assigned to a team, yet all teams should understand the entire end-to-end process.

Figure 6-3 shows a typical process flow for common tasks in a large multisite deployment. The list is not intended to be all-inclusive but rather is indicative of the process flow and task assignment you will likely encounter. The illustrated case uses a WLAN solutions provider (the "vendor") to provide additional project resources. Even if you use your own internal resources for the entire project, the tasks and process flow would remain roughly the same.

Figure 6-3. Example Site Installation Process Flow


Site Data Collection and Validation

Ensure that you have a comprehensive list of all sites in which you will deploy. Site contacts (local IT staff, reception, shipping, health and safety, and office management) should be collected in a "site database" or contact list, including phone, fax, and e-mail addresses. A "site owner" could be assigned from your IT team. This person would be responsible for configuring the devices or managing the specific site installation; alternatively, a project manager can fill this role.

Ensure that you have details such as office opening and closing times, local delivery restrictions, and any upcoming events such as office closures, construction, vacations, and so on.

Finally, it is recommended that you source or produce current floor plans for your office. You should note the location of all cabling (if possible), power outlets, and ideally the composition of internal walls, because these will affect WLAN signal strength, and ultimately quality and throughput. This information is useful during the site survey phase. Most of this information can be found in architectural or office blueprints if you have them.

Local Infrastructure Upgrade or Modification

Have your site owner (the IT staff member responsible for the site) take stock of existing infrastructure at each site before your installation team visits. The site owner should do the following:

  • Confirm that there is enough inline power or power points available

  • Make sure that you have sufficient rack space

  • Ensure that you have enough switch ports available

  • Verify that you have sufficient console ports available if you are cabling the access points for console access

Much of this is predicated upon earlier architectural decisions, but it is important that you collate and validate information on each site to avoid surprises later.

If you do not have sufficient infrastructure capacity, you should plan to modify, upgrade, or install what you need before the first site visit by a WLAN team. This in turn will affect your project plan and resource requirements. In other words, make sure the supporting or foundational enabling infrastructure is capable of supporting the access points and controllers. Don't leave yourself vulnerable to discovering halfway through an installation that you've run out of Ethernet ports on your switch, for example.

Firmware and Configuration Updates

Ensure wireless network adapters have the latest firmware and software drivers. This may require manually flashing each card or downloading the latest software. The same is true for embedded wireless clients (such as those in ASDs or embedded wireless cards in newer-model laptops). Note that for large deployments of several thousand client devices, updating firmware and software drivers becomes an increasingly complex and time-consuming challenge. We recommend a structured and tested approach for managing such environments. Refer to Chapter 8 for recommended practices.

Client Distribution

Understand how you will distribute the cards and software. You may wish to ship client adaptors to a local mailroom or IT contact for each site and delegate the distribution among your users to them. Alternatively, you may use internal mail to send client hardware to each user individually, or you may select a "client pickup" model. Ensure that your users and local staff are aware of which option you choose. Also ensure that you also provide training or informational collateral to your users at this stage. FAQs and installation instructions are usually included.

Shipping and Handling

Assign responsibility for actual shipping of hardware to each site. This includes not only the client adaptors as described in the preceding section, but also the access points and any wireless switches or dedicated hardware you may need. If you need to upgrade local infrastructure, make sure it is dispatched and installed before the wireless equipment.

The management of shipping and handling alone can be a significant administrative overhead, especially in international deployments. Ensure that you have a team that is familiar with this process. Expect customs requirements (and delays) and plan accordingly.

Decide on whether and where you will maintain a stock of standby and replacement equipment, for example, at each site or in a centralized location.

Site Survey

The site survey is perhaps the most important of all deployment tasks. This process dictates where you will locate the individual access points to provide the level of service you have defined in your architecture. The throughput you require for your applications and the estimated number of concurrent users will provide you with a rough estimate of the number of access points you will need per floor or site.

Your solutions architecture, or automated WLAN management tools, will dictate such issues as desired cell overlap, throughput required to support your applications, user to access point ratio, radio transmission power, and whether you lock your access points to a single speed (data rate). Using this information in conjunction with the floor plans you collected earlier will allow you to plan for the number of access points per site. No amount of planning can account for environmental issues impacting your WLAN, local site interference, or attenuation caused by internal office construction. You must install the access points in locations and configure their settings such that they actually provide the service you require. A formal site survey will validate this information and find the most appropriate location for the access points.

Site surveys can typically be undertaken in two ways:

  • Automatic

  • Manual

You may select an automatic site survey (sometimes called RF Prediction) and use tools provided by your WLAN equipment vendor to configure the access points once they are physically installed. These WLAN management products (like the Cisco Wireless LAN Solutions Engine or Wireless Control System) not only offer assisted or semi-automatic site survey capabilities but also allow you to import floor plans to get a visual representation of your WLAN, interference, client data, and so on. The access points are then powered up, and the centralized wireless controller or management device auto-discovers and auto-configures them with optimum settings.

In some circumstances, an automatic or assisted site survey may require you to take measurements at various locations throughout the floor to add additional data points. These can help improve the accuracy and appropriateness of the automatic configuration settings. Finally, some WLAN products (like the Cisco Centralized WLAN Solution using wireless LAN controllers) automate the access point configuration entirely and your IT staff need not configure them at all. This can offer significant savings in time, effort, and expense because your IT staff members do not have to be wireless experts or spend time configuring each access point.

The traditional site survey technique calls for a manual process. The engineers choose locations for the access points based upon "best guess," taking into account the floor plan, the transmit power, and cell overlap defined by the design and then temporarily place access points in these locations. They then perform a walkabout measuring the signal strength, cell size, and roaming characteristics using a wireless site survey software application. This can be the software provided by the WLAN equipment manufacturer (such as the site survey utility Cisco bundles into its software) or a third-party tool designed specifically for site surveys or wireless diagnostics, such as AirMagnet. If any dead spots are discovered, or if the signal strength and overlap do not meet the defined characteristics, the access points are moved and fine-tuned. Challenging environments like factories sometimes employ external, more powerful or directional antennas.

Whatever survey strategy you select, the output is the same. The result is a list of access point locations and settings that provide the coverage and bandwidth you need for that individual site. The list is then used by the implementation team to identify the exact placement of access points during the deployment, as well as by operations staff as an asset log for troubleshooting purposes.

It is important for you to document the site survey. Create a "site pack" for each location, which includes copies of the floor plans, showing the final locations of the access points, a table of all access points with information on their name, configuration (transmit power, channel, antenna type, and so on), and details such as their switch and console port number. It is also useful to include a digital photograph of the AP location. Don't forget to update the site-pack whenever changes are made or new access points are installed. An outdated site-pack can cause more problems than none at all.

Cabling

Once you have calculated the position of the access points, you must cable each location. Typically, this will require the use of plenum-rated cable (cable certified for fire resistance) to enable you to string the cable through raised floors or dropped ceilings. Each access point will require at least one network cable. If you have opted to provide console access to your access points, an additional cable will be needed. Console access will allow you to engage in out-of-band management and troubleshooting.

Finally, you will need to ensure that the access point is provided with DC current. This may require the installation of an AC mains power socket at or near the access point location. Alternatively, you can power some access points with inline power that is provided by the network switch via the Category 5 twisted pair cable. This is known as Power over Ethernet.

Access Point Installation

Next comes the physical installation of the access point. You may choose to fit the access points to office walls or building columns or hide the access point in the dropped ceiling and only leave the antennas visible. Special plenum-rated metal or NEMA enclosures are also used and are sometimes required for manufacturing or industrial areas. In any case, this is when your team physically installs the access point, connects it to the cabling previously laid, and powers up the device.




The Business Case for Enterprise-Class Wireless Lans
The Business Case for Enterprise-Class Wireless LANs
ISBN: 1587201259
EAN: 2147483647
Year: 2004
Pages: 163

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