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.
