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Why is Wifi Calling (VoWIFI) not working with tunnel mode with Smartzone?

New Contributor
I have a working setup Wifi Calling. APs and Smartzone100 is on same management VLAN. When local switching - tunnel mode on SSID is disabled Wifi Calling (VoWIFI) is working. When I turn on Tunnel mode it is not.
All is configured with "default MTU" configuration. All L3 interfaces set to standard 1500 and also L2 interfaces on switches. I didn't played with Tunnel mode (GRE or something else on SmartZone) and MTU anywhere.
When tunnel or without tunnel, users gets same private IP addresses and same public NAT IP addresses. The only difference is that with tunnel mode theirs MAC is learned on single interface on switch and with local switching on different interface. 🙂
How to solve this? Change L2 MTU on switche interfaces to APs? And also on SmartZone?


Esteemed Contributor II
Are you SURE that VoWIFI clients being locally switched can talk to the same call setup servers
that they do when tunneled to where those servers are (thru the SZ)?

New Contributor
They had the private and same public IP address and are on same broadcast network, same VLAN when tunneled or not. I tried to run ping from Wifi Clients. ping -f -l 1472. Do not fragment. So standard ping MTU. When tunneling mode is configured maximum value is 1394 that is standard - 78
VoWifi is not working over tunneled mode so i was not trying to capture that traffic.