iPad Pro Wi-Fi 6E Scanning and 6 GHz SSID Discovery

iPad Pro 11-inch (4th generation) is the first Apple device to feature Wi-Fi 6E. With the significant amount of new 6 GHz spectrum, active scanning for 6 GHz SSIDs is not practical. Other methods are being used instead. Let’s see how iPad Pro actually does it.

iPad Pro with Wi-Fi 6E

If you are an Android user, I’ve also tested Google Pixel 6 and its 6 GHz discovery here.

Setup

As of writing, iPadOS 16.1 is the latest version and that’s the one I am using for all tests here.

The access points in this test are Catalyst Wireless CW9162I-ROW APs running IOS-XE 17.9.2.

iPad Pro ignores FILS Discovery frames on 6 GHz

I am using 6 GHz only SSID (which doesn’t broadcast on 2.4 GHz and 5 GHz) and 80 MHz wide channels.

3 APs in lower 6 GHz in the UK

Of course, there are Beacon frames sent by the APs every 100 ms or so, and there are FILS Discovery frames sent by my APs every 20 ms. These FILS frames are automatically enabled on Catalyst Wireless APs in DNA persona only when the only SSID enabled on the AP is a 6 GHz one (and there is no 2.4 GHz or 5 GHz SSID). At this point, we need FILS, because at that point FILS is the only method for 6 GHz capable clients to discover 6 GHz networks.

6 GHz beacons every 100 ms and FILS frames every 20 ms

Think of FILS frames as of condensed beacons. They are nearly 4 times smaller than Beacons.

FILS frames are smaller than beacons

Unfortunately, the iPad completely ignores the FILS frames, and it has no in-band (6 GHz) method of discovering 6 GHz networks. That results in no visibility of the 6 GHz only SSIDs on the iPad, and we can’t connect.

The 6 GHz only “Cisco 6” SSID isn’t being discovered by the iPad

Airport Utility doesn’t show the 6 GHz only SSID either.

The 6 GHz only “Cisco 6” SSID isn’t being discovered by the iPad

iPad Pro only uses Reduced Neighbour Reports (RNR) for discovery

Let’s keep the 6 GHz only SSID Cisco 6 enabled, and also enable a 5 GHz only SSID called Cisco 5.

If we now do a packet capture on one of the active 5 GHz channels, we will see 5 GHz beacons. These beacons contain Reduced Neighbour Report Information Element, which announces to the client device “there is a 6 GHz AP on channel 5”.

RNR in 5 GHz beacons allows the iPad discover the 6 GHz SSID.

iPad sees both the 5 GHz “Cisco 5” and 6 GHz “Cisco 6” SSIDs

Airport Utility also reports both the 5 GHz only and 6 GHz only SSIDs.

iPad sees both the 5 GHz “Cisco 5” and 6 GHz “Cisco 6” SSIDs

By doing a packet capture on 6 GHz channel number 5, we verify that the AP only sends 6 GHz beacons every 100 ms or so. There are no signs of FILS, which is a good thing. By default, FILS is disabled. It only gets automatically enabled when 6 GHz is the only active band on the AP (with no 2.4 GHz and no 5 GHz SSIDs), because it is then the only method for a 6 GHz capable client to discover a 6 GHz AP.

6 GHz beacons without FILS, because we don’t need FILS, we use 5 GHz RNR

Apparently, the iPad only leverages Reduced Neighbour Reports for 6 GHz SSID discovery.

Does RNR included in 2.4 GHz beacons allow the iPad to discover the 6 GHz only SSID?

Andrew McHale made me to lab this up. Thank you, Andrew 😉 The short answer is yes.

This time we only enable 2.4 GHz only SSID and 6 GHz only SSID and verify that we can see them on the air using WLAN Pi in Remote Sensor mode to WiFi Explorer Pro macOS app.

Practically instantly after enabling these, the iPad discovers the 6 GHz one using 2.4 GHz RNR.

Here is the RNR Information Element included in 2.4 GHz beacons.

RNR IE in 2.4 GHz beacons tells the client to look for 6 GHz AP on 6 GHz channel 5
iPad sees both the 2.4 GHz “Cisco 2.4” and 6 GHz “Cisco 6” SSIDs

Summary

The new iPad Pro with Wi-Fi 6E only relies on Reduced Neighbour Reports (RNR) when it comes to discovery of 6 GHz Wi-Fi 6E networks. It will only discover a 6 GHz SSID, if you also enable the same or different SSID name on 5 GHz (and/or 2.4 GHz if needed).

It ignores FILS sent by the AP on its primary 6 GHz channel.

It also ignores unsolicited probe responses sent by the AP on its primary 6 GHz channel if we enable them explicitly.

It doesn’t actively scan 6 GHz to discover new SSIDs.

I recommend you enable a 5 GHz (or 2.4 GHz) SSID, which will allow the iPad to use RNR Information Element included in the 5 GHz (or 2.4 GHz) beacons. It will help other clients like Google Pixel 6, which I’ve tested here, too.

I am very happy with how well the 6 GHz discovery using 2.4 GHz or 5 GHz beacons works. It definitely is production ready. The test with only one 6 GHz only SSID on the AP is more of a corner case. Most customers I work with, if not all, will also deploy 5 GHz alongside 6 GHz, so there is absolutely nothing to worry about.

Packet capture or it didn’t happen 😉

Download 2.4 GHz an 5 GHz RNR, 6 GHz FILS, and 6 GHz unsolicited probe response packet captures from here.

Download WLAN Pi Profiler report and packet capture of 5 GHz association request, and also 6 GHz association request. We can see client’s capabilities in these frames.

Published by

Jiri Brejcha

Jiri is passionate about mobility ranging from Wi-Fi to folding bikes;-) He is a Wi-Fi Technical Solutions Architect at Cisco UK, proud member of the Cisco Live Network Operations Center deployment team, and WLAN Pi development team. If he is not working, he is most likely riding his Brompton bike.

2 thoughts on “iPad Pro Wi-Fi 6E Scanning and 6 GHz SSID Discovery”

  1. Nice write up. I guess iPad does not actively probe in 6GHz.
    I also noticed that for if you have different ssids in 2.4/5GHz and 6 GHz bands ,IPad warns that this is not good practice and also once it discover 6 GHz ssid using RNR it prompts you to add the corresponding 5ghz ssid in preferences network list.

    Please share your observations in this regard .
    Also also did you mean FILS instead of FIPS?

    1. Yes, it does warn the user when the SSID name doesn’t match. Apple recommends using the same SSID name: https://support.apple.com/en-us/HT213433

      My recommendation would be to match the SSID name, enable WPA3 on both 5 GHz and 6 GHz, and make sure that 5 GHz is also enabled alongside 6 GHz so that RNR out-of-band discovery method can be used by clients. You might still need to enable another 5 GHz SSID with WPA2 to allow clients, that only support WPA2, to connect.

      There there was a typo. I meant FILS Thanks for spotting it.

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