iPhone silent disconnect issue in guest wireless network.

[jegan_rajappa]

Problem Statement:

iPhone silent disconnect issue in guest wireless network.

Infrastructure setup:

• Guest wireless network has been configured with foreign and anchor controller with Cisco WAP/WLC and Cisco ISE with CWA.
• Open authentication.
• MAC Filtering enabled.
• SSID Session Timeout is configured with 43200 seconds (12 hours).
• User Idle Timeout is configured with 43200 (12 hours).
• WLC Model: 2504 and 5508.
• AP Model: 1602/1702/2602/2702/3702.
• Currently WLC is in 8.0.140.0 code, will be upgrading to 8.3.133.0 next week.
• Cisco ISE 2.2.
• iPhone model: I have only 5/6, IOS is upto date, but seeing the problem in all the IOS release, I mean checking from 10.0 trian, currently in IOS 11.1.2 which is latest.

Observations:

• After successful web authentication internet works well.
• Once device is locked and idle it looses the wireless connectivity silently, most of the times phone assumes wireless connection is down and start using cellular network, once phones receives any email or some traffic is generated through some background application through cellular network or if we unlock the device, phone tries to connect with wireless and it gets connected, we can see this transition in eyes easily, atleast phone takes 5 seconds to connect with wireless again, we can also see this by looking into uptime seconds in WLC client details page, without reauthentication phone has internet access reachability.
• Sometimes, approximately after one or two hours, we need to reauthenticate through CWA.
• We don’t have any issues with Andriod and windows laptop, all works as expected.
• Tried enabling/disabling client load balancing and Client Band select through SSID advanced settings, no luck.
• Debugs doesn’t give much details.
• Noticed this issue in ISE 1.3, so upgraded to 2.1, same issue, then upgraded to 2.2, still same issue.
• Noticed this issues in most of the iPhones.
• Same iPhones don’t have any issues with WPA2-AES-PSK, but noticing this issues only with open authentication setup.
• Tried enabling client user idle timeout in SSID advanced settings, no luck.
• Tried setting only 802.11a radio policy, no luck.

Tried raising several TAC case, no resolution, hence starting discussion here to see if anyone else experience same issues.

[jegan_rajappa]

Here is the video showing the event from mobile perspective

[Freerk Terpstra]

Wow, this topic keeps you busy. I still don't have a quick fix, but maybe my story can help you in some way.

Since my last reply in November 2017, I have experienced the same behavior as shown in your video myself. This was with both "open" and "PSK" networks and with iOS 11.4. After a few of these events in a short amount of time, the iPhone stopped this behavior and started the "send every 90 second a null frame" routine instead. The only thing that I found out, was that the iPhone reported "device idle" as "last disassociation reason" when it connected back to the network. The funny thing is that the battery was fully charged, the Wi-Fi signal was excellent and there were also applications active in the background, so no reason for the iPhone to go idle if you ask me.

You can find this specific Apple "last disassociation reason" while performing a "client debug xxxx" or on the GUI of the WLC when the iPhone is associated to the network again. I'm wondering if you see the same and with which iOS version you are testing, since I haven't seen it with iOS 12.3.

Please rate useful posts... :-)

[jegan_rajappa]

I am seeing many null frame within a second in wireshark capture (PFA).

iPhone OS is 12.3.1

WLC has 8.3.150.0

WAP Model: 2602 and 2802

Based on Debug Analyzer, it seems client makes new association every second which looks weird.

[Freerk Terpstra]

It is a wild guess, but I would not be surprised if Apple has some "privacy feature"which makes the client goes silent on an open network.

Since this issue is easy to reproduce I would setup some a sniffer access-point and capture the wireless frames send on the channel the iPhone is connected on. The network is open so you don't have do to anything special to be able to look at the payload of the traffic as well. During this test I would also monitoring how the wired network "sees" the client; is the MAC address still known and is there an ARP entry on the default-gateway for the client?

Please rate useful posts... :-)

[cdchamberlin]

Hi Jegan, 

I was experiencing the same issue that you noted in Nov, 2017. However, after trying many different techniques and tuning, I did find a simple fix that resolved the silent disconnect issue I know a lot of engineers are facing. 

If you come across an iOS device silently disconnecting from your wireless, please try the following. It's a simple fix and quite honestly, resolved many of the iOS issues customers were facing. 

Join Wi-Fi networks automatically

Your iPhone, iPad, and iPod touch can remember network and login information so that you can automatically reconnect to that network when you're in range.

If your device doesn't automatically join a captive Wi-Fi network, follow these steps:

1. Tap Settings > Wi-Fi.
2. Tap  next to the network name.
3. Make sure that Auto-Join is on.

If you don't want to connect automatically, turn off Auto-Join. To see the Welcome screen the next time that you connect to the network, turn off Auto-Login.