Wireless networks are not something you want to just set up and forget. Though some networks don’t require a lot of upkeep, some may. Changes in how the network is used, new wireless devices, neighboring networks, and security issues are all reasons a network may need more maintenance and attention in order for the Wi-Fi to work as desired. Here I will discuss these issues and offer tips on how you should maintain your wireless LAN.
Consider network usage changes
Changes in how Wi-Fi is used can have major impacts on its performance. Say a wireless network was initially deployed with just basic web browsing in mind for employees, but the network was opened up to guest use during large events. This could cause instability and maybe even network failure during these events.
Another possible scenario: the wireless network was initially designed for coverage only in the main areas of a building, but Wi-Fi thermostats were installed throughout, including areas where signal wasn’t a priority before. In this situation, there simply may not be enough Wi-Fi signal in the nook and crannies where these thermostats are installed. Additionally, low signal means slower speeds and data rates. This equates to more airtime required to send and receive data, negatively affecting the performance of other clients as well, even those that have perfect signal strength.
As you see, changes in Wi-Fi usage can have big impacts. Periodically, the wireless network’s usage and it’s actual and required specifications should be evaluated. Evaluation of usage includes identifying exactly what devices are connecting and what they’re doing via the Wi-Fi. These can then be used to compare to the actual and required specifications, such as signal coverage, throughput, user capacity, and roaming between access points.
Relinquish older wireless devices
Wireless technology is constantly improving. The earlier standards, such as 802.11a, 802.11b, and 802.11g, are much slower than the newer ones, such as 802.11n or 802.11ac. Though most of the wireless network gear today supports these older standards, using an older wireless device on them not only provides a slow link for that user, but can slow the entire network down. This is due to the protection and compatibly measures the network must take to support the older device.
Try to replace older wireless devices with newer ones. Consider disabling support on your wireless network for some of these older standards as well, so someone that brings in an old device won’t affect the entire network. You can most likely get away with disabling 802.11b support, and possibility 802.11g. Additionally, you could consider disabling some of the lower data rates so devices are more likely to roam to better access points when on the fringe of coverage from a current access point.
Utilize the 5GHz frequency band
The 2.4GHz frequency band is by far utilized much more than the 5GHz band. Though 5GHz devices have less range, the frequency band provides many more usable channels, which reduces interference from neighboring networks and capacity issues when trying to support large numbers of Wi-Fi users.
Since more dual-band devices supporting making their way into the marketplace, I recommend deploying dual-band capable access points. Furthermore, I suggest using any band steering functionality on the access points. Band steering will try to push dual-band capable devices to connect via the 5GHz band, rather than leaving the decision of 2.4GHz versus 5GHz up to the user or device.
Check for interference
Since the Wi-Fi frequency bands are relatively small and are used for other radio communications as well, interference can be a major issue. Interference can be both constant and intermittent, so it’s a good idea to keep tabs on it. I suggest employing any interference detection or alerting functionality offered by your wireless access points
I suggest performing full on-site RF site surveys periodically to check for channel usage and interference.
Double-check channel usage
Just about all wireless access points include an auto channel feature that will automatically choose the “best” channels to use. However, I have seen these select interfering and overlapping channels before. Therefore, if you utilize automatic channel selection, I certainly recommend double-checking to ensure they are in deed choosing the best ones.
One basic fundamental rule for 2.4GHz: try to use only channels 1, 6, and 11 since there is overlap between channels. For more details, see Tips for Assigning Wi-Fi Channels.
Just like for interference, I suggest performing full on-site RF site surveys periodically to double-check automatic or manually assigned channels. Any changes to access point locations and changes to neighboring wireless networks can cause significant issues.
Check for rogue access points
Rogue access points are those that are broadcasting without being properly vented by IT or aren’t correctly secured. Employees could bring in a wireless router from home, hoping to fix a low signal issue. Even worse, someone could set one up to intentionally hack your network, giving them wireless access they could utilize even in the parking lot.
Given that they’re wireless and they can create a huge security hole in your network, rogue access points need to be detected and fixed as soon as possible. Additionally, they could cause performance issues if they aren’t configured on the right channels.
Re-evaluate wireless security
As you likely know, security risks and protection measures change just about every day. So periodically, re-examine your Wi-Fi security. Perhaps start with the basics: ensure all private wireless access is secured by at least WPA2 security with AES encryption. Since the personal mode, technically called pre-shared key (PSK), uses a static global password, try to use the enterprise mode. Its 802.1X authentication allows each user to have unique login credentials.
If you do use the personal mode of WPA or WPA2, at least ensure the password is changed periodically, especially after an employee leaves the company or a device used on the network is lost or stolen.
For more info on Wi-Fi security, read Ways to Increase Wi-Fi Security.
Tweak the advanced settings
There are many more wireless settings than SSIDs, channels, security, and other basic settings. The advanced settings can help you tweak the wireless network, especially useful on busy or high capacity networks.
There are a couple settings to consider enabling that can shorten packet sizes or transmission times to help increase performance:
- Short Preamble Length
- Short Slot Time
- Short Guard Interval
- Frame Aggregation
If you aren’t using roaming sensitive devices or applications, also consider increasing the beacon interval to reduce airtime of management traffic. Additionally, if there’s a large number of collisions and/or interference, consider adjusting the fragmentation and RTS thresholds.
As mentioned a few times, a periodic full RF site survey should be performed. During these surveys, you can detect and investigate just about all the issues we discussed. During an onsite walk-around with a Wi-Fi analyzer you can check for signal and noise levels, neighboring networks, and look for co-channel and other types of interference. You could also evaluate the security settings of the access points and detect any rogue access points.
Though free simple Wi-Fi analyzers could do for surveying smaller networks, consider using full-featured commercial tools for larger networks, such as AirMagnet WiFi Analyzer. Additionally, I suggest using tools that can show the signal levels and other collected data on heat-maps, such as AirMagnet Survey, Ekahau Site Survey, and TamoGraph Site Survey.