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Wednesday, February 12, 2014
[accuvant] WiFi Management Tools Help Ensure WLAN Health
For many organizations, the wireless local area network (WLAN) has changed from an optional item to a mission-critical service. Customers and employees automatically expect WiFi connectivity to get their work done. However, many wireless networks were originally designed for intermittent use, primarily by laptops. They may not be able to cope with the increased traffic that a busy WLAN experiences today. This can lead to user complaints that the wireless connection is slow and frequently disconnects, or comments like “This never happens when I use my mobile device at home.”
How can you tell if the complaints indicate bigger problems with the wireless network design? Many management platforms give you information such as user counts and coverage maps, but this really doesn’t explain why particular devices are having issues. The most common troubleshooting method entails finding other users in the area with similar problems and then trying to extrapolate if the issues lie with the device itself or with the network. This can provide some insight into the problem, but often problems that present themselves on heavily loaded wireless networks are difficult to pin down. Also, it doesn’t explain why a device may work fine elsewhere but not in the office.
Like any other complex technology, wireless networks require maintenance and the occasional tuneup to run efficiently. WLAN use has changed significantly during the past few years, so an organization may discover the need to redesign its wireless network to handle large numbers of mobile clients. At an individual client level, the organization will need troubleshooting tools to determine why a connection is flaky.
For example, a wireless scanning tool can gather basic information on the number of wireless networks present in an area, their signal strength, and if they are close enough to cause issues. Metageek’s InSSIDer is one tool that can be used for troubleshooting at this level. There are free (Home) and paid (Office) versions, both of which include information to help customers learn how WiFi works and provide information and tips about the health of the WLAN. The Office version also offers the ability to see radio frequency (RF) interference, which is caused when two devices broadcast on the same frequency simultaneously. Non-WiFi devices and other WiFi devices broadcasting on the same channel can cause interference.
WLAN professionals use a range of other tools to troubleshoot wireless network problems. They begin by doing a health check — gathering information about issues in the environment and complaints that users are reporting. A good health check toolkit usually consists of site survey software to capture a snapshot of the wireless network; spectrum analysis software to provide non-WiFi interference packet capture; and analysis software, which looks inside the packets going across the WLAN to discover errors or misconfigurations that may be disconnecting clients.
These products are available from companies such as Metageek, Fluke Networks, Tamosoft, Ekahau, Wildpackets, and Riverbed, which supports the open-source Wireshark network protocol analyzer. Such tools provide the ability to narrow down a problem and find the cause. However, determining the root cause can be very difficult when the problem is intermittent. It’s critical to have an experienced WLAN professional with knowledge about WiFi design and operation to be successful when using these tools.
Using network-level tools such as wireless intrusion prevention systems (WIPS) can help track network performance over time. Wireless network management systems also gather performance-related information directly from the wireless access points. The networking technology company 7signal took a page from the cellular world and developed a product that can be placed in the network, monitoring performance from the WiFi client’s point of view over time to provide detailed reports and analysis of wireless issues. Its product is proactive in discovering wireless issues by looking at the network and reporting problems as they occur — but before a user gets frustrated enough to call the help desk.
The key to managing wireless networks effectively is having the knowledge that RF is constantly changing, and that a WLAN’s health must be checked over time to verify that assumptions made at the start of the network’s life are still true. Providing WLAN administrators with tools to test and verify those assumptions gives better insight and reduces complaints as network use increases. As mobile devices become more critical in the enterprise, it’s important to conduct health checks regularly, so the WLAN can remain flexible and cope with usage changes.