I have an intermittent problem with my mesh network at the office.
I have 2 hap ACs (ROS 6.39), configured to use dynamic mesh between the 5 ghz radios.
Same SSIDS, security settings for both 2.4 ghz, to allow the client to decide which radio to connect to.
This works wonderfully! … except sometimes I notice that, after moving from one spot to another, I lose connectivity on the client.
I check the client (iphone), and notice that even though it is still connected to the AP, it is not getting a valid address from the dhcp server, and defaults to 169.254…
I need to turn wifi off and on again on the client, and then everything works again, it gets a proper address, connectivity, etc.
After some investigation, I am able to reproduce this problem:
Using an IOS device, while being close to the 1 AP:
- Force the client to connect to the 2.4 ghz radio (using an access list that denies association the client on the 5ghz radio)
- Once it is connected, disable the rule to deny association of that client to the 5ghz radio, and WAIT. After a few minutes, the IOS device will seamlessly connect to the 5ghz radio, and then it loses connectivity, doesn’t get a proper IP address. Looking at the registration table of the AP, I can see the the client IS connected to the 5ghz radio, strong signal etc.. It will remain like this until I disable and enable wifi on the client. Then, it will connect to the 5ghz radio again, and everything works again.
This is a real world scenario, where if I happen to be far from the AP, it connects to the 2.4 ghz radio, but when I am nearer to it, it will switch over to the 5 ghz radio and lose connectivitiy.
After further investigation, I noticed that what was happening was that when this switch from the 2.4 ghz radio to the 5 ghz radio happens, the MAC address for the device disappears from the Mesh FDB table, then, even though then client is still connected to the AP, there is no connectivity to the network.
When I disable and enable wifi on the client, it connects to the same radio, but gets access almost instantly and I see the client’s MAC address added to the Mesh FDB.
I also notice the way the AP handles the switch from the 2.4 ghz radio to the 5ghz radio, according to the logs:
While the client is connected to the 2.4 ghz radio, it first connects to the 5ghz radio and then only disconnects from the 2.4 ghz radio (disconnected, registered to other interface).
So I’m guessing that what is happening is that when it connects to the 5 ghz radio from the 2.4 ghz radio, this event tries to add the client’s MAC address to the mesh FDB, but fails, because it still exists in the FDB (at that point, it is still connected to the 2.4 ghz radio), THEN, when it disconnects from the 2.4 ghz (disconnected, registered to other interface), this event removes the Mac address from the FDB and the client loses all connectivity.
Is there anyway to fix this (other than having different ssids for both bands)?
Thanks