When a Mist AP cannot reach the Mist Cloud, can end users with a wireless connection still communicate with the internet? With the local network?
If config persistence was enabled on the AP before it lost connectivity to the Mist cloud, the AP will still be able to provide WiFi. The same goes for APs that experienced power failures. If config persistence was already enabled, the AP will be able to provide WiFi after powering back up.
AP Config Persistence: By default the AP only keeps critical information such the Static IP (if used). In the event of a power failure the AP will need to talk to the Mist cloud to come back up. If you enable config persistence then the AP will remember the full config and come back up regardless of internet connection.
To enable AP config persistence, go to Organization > Site Configurations and select your site. In the site configuration page, you will find an AP Config Persistence box, where you can select Enable. Once you have AP config persistence enabled on the site, APs in the site will be able to serve clients regardless of Internet connection.
Will there be any impact to users currently on the site when we enable AP config persistence on the site?
Enabling AP config persistence will not cause any AP reboots, and will not impact any current users.
Is it recommended to use AP Config Persistence?
It is a useful feature and we recommend that you enable AP config persistence on your sites. If the option is checked and the AP loses connectivity to the cloud the WiFi should not have any impact unless the WLANs have user-based WxLAN policies or if Bypass guest/external portal is disabled.
Does this mean that users can communicate with the internet and the local network even when the AP is in a “Disconnected” state as long as AP config persistence is enabled?
Yes, users will still be able to communicate with the internet because WiFi is not affected. Corner cases in which WiFi will be affected are mentioned above: If the WLAN has user-based WxLAN policies, or if Bypass guest/external portal is disabled. In these cases users will fail to connect to the WiFi.
If an unstable WAN link or TCP connection failure occurs, do the APs lose the configuration? Are the clients disconnected by the APs?
Yes, if the WAN Link is unstable APs will lose connectivity to the cloud. During this period APs will not be able to service the clients.
But as mentioned above, if AP Config Persistence is enabled, the APs will still be able to provide WiFi to the clients and their configurations will not be lost.
How do you detect cloud unreachability?
Ap sends ap-stats to the cloud every 2 seconds. If the cloud doesn’t receive AP stats for 90 sec then the cloud will mark the AP as disconnected.
How does the AP determine that access to the cloud has been restored?
The AP will try to reach out to ep-terminator.mistsys.net. Once it is able to reach out to the domain and receive data from the cloud, the AP will know that the cloud connection is restored.