Identifying 802.11ax Support with Wireshark

We’re beginning to see vendors come out with their latest and greatest access points touting 802.11ax (Wi-Fi 6) support. 

At the Cisco JustTheTech event, I was given a Cisco C9115 to try out for the purposes of testing Wi-Fi 6. At the time, the controller code didn’t have these features enabled. 

How can a vendor come out with a Wi-Fi 6 AP but not have those features ready to go? The hardware is capable but in software, it had to be turned on.

In this blog post, we’ll look at how to identify 802.11ax support using Wireshark.

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802.11ax – High Efficiency

At the time of this blog post, 802.11ax is still in draft form and the Wi-Fi Alliance had branded it as Wi-Fi 6. The developers at Wireshark added support to view the information elements and fields for 802.11ax.

You do not need an 802.11ax capable device to view some of these information elements. Using a frame capture tool such as Airtool or the Ekahau Sidekick, we can collect this information and view it within Wireshark. 

I’m using Wireshark version 2.9.0. 

If you’re interested in learning more about 802.11ax, please check out my podcast series with François Vergès.

Cisco C9800-CL 802.11ax Configuration

It’s important to note in the configuration, 802.11ax must be enabled. Using the C9800-CL, the option is enabled under High Throughput and under the WLAN configuration.

Configuration -> Radio Configurations -> High Throughput

Additionally, 802.11ax features must be enabled on the WLAN.

A Beacon of 802.11ax

The most notable place to see 802.11ax support is in the Beacon frame. After viewing the HT and VHT information elements will be an 802.11ax High Efficiency (HE) information element which holds many more details about the support of 802.11ax.

You’ll notice HE Capabilities and HE Operation below in the screenshot.

Expanding the HE Capabilities information element, we can see all the details supported on the Cisco C9115. There’s a lot to unpack here and in the following screenshots but I will not dive into those details here.

The HE Operation information element contains more fields, including BSS Color.

What about spatial stream support? You can verify that within the Beacon frame as well by looking at the Supported HE-MCS and NSS Set field.

What’s In the Association Response

I noticed there were more details under the Association Response from the AP. In the Beacon we did not see TWT supported. But in the Association Response we are able to see TWT Requester Support as Supported.

Should You Buy 802.11ax Today?

No. It’s too early to say how 802.11ax will perform with new hardware. There aren’t many 802.11ax capable clients. In my lab I used a Samsung S10 and an Lenovo with an Intel AX200. A lot more real world testing needs to be done to validate the operation of 802.11ax in today’s mixed environments.