The Top 8 Things Your Wi-Fi Test Application Is Not Telling You | NETSCOUT
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The Top 8 Things Your
Wi-Fi Test Application Is Not Telling You

There are many smartphone and tablet applications available for testing Wi-Fi. Most of them are either free or under $100, making them an attractive choice (at first) for people who must verify and maintain Wi-Fi services and are looking to do it on the cheap. But time is money, and the cost of not solving Wi-Fi service issues because your test application is incapable can be much higher than the cost of a professional and highly effective tool.

1. Channel utilization due to Wi-Fi traffic

What it is

The percentage of time that a channel is utilized with Wi-Fi traffic. This is not the same as the number of access points on a channel.

Why it’s important

A Wi-Fi channel is time-shared among all access points and client devices that are on the channel in an overlapping coverage area. Every time one AP/client device transmits, all other devices on the channel have to wait, and enough waiting adds up to slowness. Thus high-channel utilization is a primary factor of slow performance and needs to be accurately measured.


2. Channel utilization due to interference

What it is

The percentage of time that a channel is utilized with non-Wi-Fi signals from interference sources.

Why it’s important

When interference signals occupy a Wi-Fi channel above a certain power level, Wi-Fi devices cannot transmit. With less time to transmit Wi-Fi traffic, Wi-Fi devices experience slow performance. Also, if the interference signals are high enough and with enough airtime, they can disrupt Wi-Fi connectivity.


3. Retry Rates

What it is

The percentage of Wi-Fi frames transmitted that must be re-transmitted. A retry rate should be measured for a specific device’s transmissions, or for all transmissions on a channel.

Why it’s important

When a device transmits a Wi-Fi frame, it must receive an acknowledgement from the recipient. If it does not receive an acknowledgement, it will re-transmit that frame. A frame may not reach its destination due to poor transmission conditions such as interference, noise, signal attenuation, or congestion.

Retries have the impact of using up valuable channel air time, resulting in higher channel utilization which will slow things down for everyone on that channel. A high retry rate is also a clear indicator of poor transmission conditions.


4. Where is that rogue access point or unauthorized client device?

What it is

An unauthorized access point operating in the same area as an authorized network. It may or may not be connected to the wireline infrastructure network.

Why it’s important

Unauthorized, or rogue, APs (Access Points) pose a significant security threat. They can also negatively impact performance for authorized users. Even rogue access points that are not connected to the wireline network can be security risks for unknowing users who connect to them. Locating them swiftly is critical to removing them and mitigating the security and performance risks.


5. What clients are connected?

What it is

Visibility into what user devices, or clients, are associated with what SSIDs and access points.

Why it’s important

Understanding the network infrastructure (access points) is important, but knowing client connectivity can help immensely in determining if too many clients are causing high-channel utilization, clients are connecting to access points they should not be (e.g. too far away), legacy 802.11b clients are connected that should not be, unauthorized devices are connected, and many other issues. This is also valuable to troubleshooting specific client-connection problems, for example, whether the user's client device is connected to a specific access point. Also having visibility into the data rates at which clients are connected is vital to diagnosing performance issues.


6. What clients are not connected but are probing for networks?

What it is

Visibility into what user devices, or clients, are not associated to an SSID but are transmitting probes for SSIDs.

Why it’s important

An unassociated client transmits probes for SSIDs that it is looking for, such as SSIDs the user has previously connected to. These client probes utilize airtime on multiple channels, too many of which can have a real impact on channel utilization and performance. It is also a security issue. A probing client can be a target for an attack and it can also be a source of an attack. And in general, knowing what types of devices are in your environment, regardless of whether they are associated to a network, is helpful in understanding the use-case needs of your network.


7. What networks services are working (or not)?

What it is

Beyond the wireless connection to an access point, services such as DHCP addressing and DNS, as well as LAN, WAN, and broadband connectivity to network resources, must be working to provide a useful service over Wi-Fi.

Why it’s important

Often when a Wi-Fi user cannot access a web site or download a file, the problem gets attributed to the wireless connection. But the problem may reside on the wireline side. DNS may not be available, for example, or there is no connectivity to the internet. Knowing this can save a lot of time rather than looking for a wireless problem that does not exist.


8. Detailed access point configuration

What it is

The many 802.11 configuration parameters for which an access point is set.

Why it’s important

An application may tell you what security is used by an access point (e.g. WEP, WPA2 personal, WPA2 Enterprise) but there are many more details that can cause a network to not work: (A) What data rates are supported; (B) Are legacy devices supported; (C) What channel widths are supported; (D) Is shortguard interval used; (E) How many spatial streams are used; (F) and many more.


Professional tools from NETSCOUT will make you the hero when you are able to get to the root cause of problems and get the Wi-Fi service running fast and smooth.

The AirCheck G2 is the leading handheld Wi-Fi tester for professionals because it enables them to address most Wi-Fi issues fast. The custom radio provides the key tests and measurements described here, and the small but rugged handheld form factor makes it suitable for any environment.

AirMagnet Wi-Fi Analyzer PRO is the industry's leading software wireless network troubleshooting solution that allows IT pros to easily and accurately analyze 802.11a/b/g/n/ac environments — without missing any traffic or getting bogged down in time-consuming packet analysis.