Without doubt, one of the best tools on the market for maintaining great Wi-Fi is the NETSCOUT AirCheck G2 Wireless Tester. Its ease of use, portability, reliability, depth of visibility and cetralised reporting capability have made it a worldwide success and staple part of the engineer’s toolkit. The purpose of this post was to highlight a few examples of how to use the tool to address some of the most common considerations, and of course issues, presented by Wi-Fi. Firstly, lets take a look at the tool itself:
On the AirCheck G2 we have a large clear and responsive touch screen, a mounting point for an external uni-directional antenna, a 1Gbps Ethernet port for testing backhaul connectivity and PoE and a couple of USB slots for attaching devices, memory sticks etc.
For the purpose of completeness of visibility we will assume use of the NETSCOUT AirCheck G2 TA Kit which includes a few additional handy extras including the external antenna and holster but a clue in the ‘TA’ part of the name, the Test Accessory. This is a small footprint device, which is used to remotely connect to the AirCheck and provide iPerf testing – to get network throughput performance statistics. Here is what is in this ‘TA Kit’:
Verify The Network Deployment
Using the AirCheck G2 we can check the ability to establish a connection to the network and access core services such as DHCP and DNS, can it resolve a web address, and how long did this all take. From this simple workflow, you can ensure that everything from a connectivity perspective is as expected:
Verify Network Performance
Using the AirCheck G2 paired with the Test Accessory, we can now validate performance to a remote device. Here’s how:
- Connect to a network
- Select iPerf Test
- Select iPerf Server or Test Accessory to test against
- Click ‘Start’ to begin your test
This now gives us an indication that the network is available, we can connect and gives an indication of its performance.
Auto Test is a really handy, user configurable set of tests that can be run with a single touch to validate network health with a ‘Pass or Fail’ indication. Using this feature, the AirCheck G2 is testing the following 5 elements:
- 802.11 Utilisation : Reports top 3 channels in each band (2.4/5ghz) with highest Wifi traffic utilisation.
- Non-802.11 Utilisation : Reports top 3 channels in each band (2.4/5ghz) with highest non 802.11 airtime utilisation. This indicates the presence of interference sources and high noise.
- Co-Channel Interference : Reports the top 3 channels in each band (2.4/5ghz) with the most AP’s on the same channel that exceed the minimum signal level threshold.
- Adjacent Channel Interference : Reports the top 3 channels in 2.4ghz band in which AP’s might experience adjacent channel interference. For each channel of which at least one AP is found, the feature counts how many access points are operating on other channels that are overlapping with that channel.
- Network Quality : Verifies coverage, interference, security and ability to connect to specified networks, along with the availability of critical services such as DHCP and specified network targets.
Using the onboard Wi-Fi radio of the AirCheck G2, we can sense and classify (when possible) sources of interference that are having a detrimental impact to network performance. Sources which are identified are as follows:
- Baby Monitor
- Cordless Phone
- Game Controller
- Motion Detector
- Narrowband Jammer
- Video Monitor
- Wireless Bridge (non-802.11)
- Wireless Mouse
- Wireless Video Camera
- + Possible Interferer and Unclassified Interferer
By getting close to the area in question and running this test you can quickly see if there is anything that could be causing a problem, how strong the interference source is, on what band, what channels are impacted, how often and for how long. From here you can even locate the source and either isolate it, or in some cases engineer the network around around it so that it no longer poses a problem.
Optimising the Network Using the AirCheck G2
The ‘Channels’ screen on the AirCheck G2 gives an excellent insight in to channel configuration, channel utilisation and also non-wifi channel utilisation across 2.4 & 5ghz bands. Using this screen, we can see the entire Wi-Fi spectrum at a glance and also view how the channels are overlapping
When optimising the channel domain, some considerations are:
- Are there too many APs on a channel?
- Are there AP’s on overlapping channels in the 2.4ghz band (2, 3, 4, 5, 7, 8, 9, 10)
- Is 802.11 airtime utilisation too high?
- Is Non-802.11 airtime utilisation too high?