I passed the Cisco CCNP Enterprise Core test (350-401, Encor) yesterday. It closed a long period of studying and preparing. To help other candidates to find study resources I will in this article describe which one I used.

During 802.11ax UL OFDMA TXOPs, clients that are assigned a resource unit (RU) by the AP for uplink data transmission will send data in that specific time slot.
But do clients use this time slot efficiently? Wireshark doesn’t give the answer

Let us have a deeper look in an example

802.11 ax UL OFDMA is one of the new and key features of 802.11ax or WiFi6. I’ve been able to capture this in my lab network and in this article I will explain key elements on how I do it, and what I look for in this capture

The 802.11ax amendment was built to increase the efficiency of WiFi. One of the new features is OFDMA or the capability to send data to several stations simultaneously, multi-user operations.
One of the benefits of OFDMA is to decrease the duration it takes to send the data to several stations in relation to single-user operations. Especially for smaller frame sizes, but for which?

In this blog, I will check the trade-off between SU and MU operations in 802.11ax for three typical scenarios.
You will be amazed, I was

I have been selected as one of the finalists for the Cisco 2021 IT Blog Award

The 802.11 Block Acknowledgement frame (BlockAck) is a powerful frame to predict the data flow in a WiFi network, both when the data frames are visible in a frame capture and not.

Let us use Wireshark and the I/O Graph to visualize it

If you really want to dig into 802.11ax frame formats, a wireless capture (pcap) and Wireshark is a great way of doing it.
In this blog, I will dig into the preamble of an 802.11ax frame and point out several items to look at. I will also find information from the first part of the preamble, the legacy preamble

When interpreting wireless captures it is not always easy to capture the data frames because they are usually sent with complex modulation and coding schemes. The quality of the capturing NIC is also important.
But management and control frames are easier to capture because they are sent with legacy frame format (802.11b/g or 802.11a).
The BlockAcknowledge frame (BA) is the frame used by the receiving station to send back to the transmitter the status for what the receiver has received without corruption.
The last two years I have seen two different behaviors for the BA, one according to the standard and the other with a strange behavior
Let us dig into it

Frame capturing of 802.11frames, WiFi, is a important task in managing and troubleshooting WiFi networks. In the earlier days there were different methods of capturing these frames, but now when 802.11ax (WiFi6) is in the marked the variety in methods is limited.

Capturing the management and control types of frames that normally use legacy frame formats like 802.11b/g in the 2.4GHz band and 802.11a in the 5GHz is still easily done, but capturing the data frames with 802.11ax frame format is more tricky.

I will in this blog compare 802.11ax frame capturing using a Jetson Nano with Intel ax200 wireless NIC and a Cisco C9115-AXI in sniffer mode

This is a method of having a SpeedTest service available during AP on a stick survey (APoS), with only an AP, PoE battery, and a WlanPi available

This is probably described earlier, but I do it anyway