Planning WLAN Operational Support
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Operational support generally contributes to nearly fifty percent of the total lifecycle costs of a wireless LAN. As a result, be sure to fully plan related operational support. Support elements for wireless LANs are similar to those for typical wired networks; however, wireless support must take into account the uniqueness of radio wave propagation.
Configuration Management Basics
Configuration management consists of controlling changes made to the WLAN after installation. Changes made to an existing WLAN may involve installing or moving access points, altering access point configurations (e.g., RF channel), or updating firmware. In larger projects, especially those that have some sort of government control, configuration management may also be necessary to keep requirements from expanding endlessly.
Network managers need to review any changes that may impact the performance or security of the WLAN. The review ensures that relevant impacts are taken into account that involves additional costs and use of resources necessary to support the request. In some cases, changes may merely involve supporting a larger number of users, who may or may not require modifications made to the network. Other instances could include a need for wider RF coverage and additional access points.
Important Underlying Processes
A company should utilize a change request form as an input into the configuration management process. The purpose of this form is to summarize the requested change in a manner that makes it fairly simple to determine the level of review needed to accept or reject the proposed change. For instance, the addition of a new application would likely require the review by security and engineering functions to determine whether mechanisms are in place to safeguard the application and provide adequate levels of performance.
A key aspect of configuration management includes the development and management of a baseline architectural design and support plan. When someone proposes or requests the deployment of a wireless LAN or a change that prompts the modification to an existing wireless LAN, then the company should utilize this baseline as the basis for validating and verifying the design and assessing the impacts. This process includes determining the impact of the proposed change on the overall wireless LAN and peripheral systems.
The implementation of an effective configuration management process also includes the establishment and use of a configuration management database, which includes a listing of all installed components, configuration settings, and applicable diagrams that document the current state of the wireless LAN. This database should include a listing of all hardware and software (including configurations) that are part of the wireless LAN. As the company accepts changes to the wireless LAN configuration, they would then update the database to reflect the new state of the system. This avoids having the only knowledge of the wireless LAN composition from leaving the company as network management staff move on to jobs elsewhere.
Configuration Change Considerations
Anyone, including users, should be able to request a modification to the wireless LAN. The following offers some examples of typical configuration management items that may require attention:
- RF channel. The maintenance staff could request adjusting the RF channel on a specific access point, possibly because they have evidence that the access point is interfering with another one. Before authorizing this change, be sure to think about effects of the new channel setting on all access points. In order to maximize the capacity and performance of the wireless LAN, access points within range of each other should be set to non-interfering channels.
- Transmit power. In some cases, a request may come about because of the need to either increase or decrease the range of a particular access point. For example, an access point may need to be set to a lower value to enable the installation of additional access points for the purpose of reducing cell size and the number of users associated with each access point. The overall effect of this could be to increase the throughput available for each user. When making this type of change, ensure that it will result in adequate coverage in all user areas. If making a change that increases transmit power, be certain that inter-access point interference is kept to a minimum.
- Applications. A user or manager may request a new application, such as video conferencing, that will traverse the WLAN. As a result, carefully size up the network to ensure that there will be enough capacity to support the application along with existing ones. Other cases may include setting up public wireless Internet access to an existing wireless LAN that currently only services company applications. In this case, some engineering will likely be necessary to keep public and company traffic separate and secure.
- RF coverage. If users complain that holes exist in the coverage throughout some parts of the facility, then an alteration is necessary to improve coverage. This will likely entail the repositioning or installation of access points, but try making configuration changes (e.g., transmit power) before spending money on new hardware.
- Firmware. A company will need to periodically update the firmware of the access points and possibly radio card in user devices in order to take advantage of performance, security, and interoperability enhancements that the vendor offers. Before actually updating the firmware in operational access points, though, perform enough testing with the new firmware on access points in a lab environment to ensure that the firmware will support all applications in use on the wireless LAN.
- Security improvements. A company may discover that their existing wireless LAN doesn't have security mechanisms that fully protect company assets. In this case, the additional of access controllers or enhancements to access points may be necessary. Of course these types of changes should only be made after defining security requirements and analyzing potential solutions.
Stay tuned! In part II of this tutorial, we'll take a closer look at network management as we continue through various aspects of planning operational support for wireless LANs.
Jim Geier provides independent consulting services to companies developing and deploying wireless network solutions. He is the author of the book, Wireless LANs and offers training focusing on wireless LANs.