I have a 4430 acting as a core router with no firewall and multiple sub-interfaces on the Gig-E port. I'm using Gi0/1.1 as my primary LAN with an address of 10.100.90.1. I'm using Gi0/1.100 as my internal WiFi network obviously on the same physical port. I've turned on IP multicast-routing and IP PIM sparse-mode on both interfaces. router pim-sparse at the global level with an rp-address of 10.100.90.1. My Airprint devices are on the 10.100.90.x network but the WiFi devices (10.100.80.x) cannot see the printers.