So, we have a /24 subnet with different sections of our building on different vlans for our phones, and mDNS only seems to work for finding a DPMA configuration server when phones are on the same subnet as the server. Is there a way to configure either the server or the switches to forward mDNS traffic to the other subnets so the phones can find the server so we don’t have to manually type in the IP of the config server when configuring the phones?
You can co-opt Option 66 from your DHCP server - https://wiki.asterisk.org/wiki/display/DIGIUM/Provisioning#Provisioning-DPMAandSwitchvoxConfigurationwhenMulticastisNotAvailable
to point phones using it.
The server can’t forward mDNS across subnets to which it’s not attached - multicast doesn’t work that way.
If you’ve got other machines on other subnets, you can craft a special Avahi services file. See the firmware Avahi services file from the aforementioned link, and replace the firmwareURL, firmwareVersion,Dx0File and serviceType lines with something like:
remembering that you’ll need to set the port, above that, to 5060, or whatever you’re running Asterisk on.
Providing advice on configuring a switch to forward Multicast traffic across subnets is beyond the scope of anything I could do here.