Application Scenarios for mDNS Relay
As shown in Figure 1, an enterprise provides wired and wireless networks, the router functions as the enterprise egress gateway, packets between an AC the APs are forwarded at Layer 3, and Apple TV_1, Apple TV_2, and printer are connected to the AC across network segments. The destination multicast address 224.0.0.251 of mDNS used by Bonjour is only valid within a Layer 2 broadcast domain, so the AC as the mDNS gateway cannot receive service advertisement messages from Apple TV_1, Apple TV_2 and printer. The mDNS relay can be configured on Switch_1 and Switch_2 to convert multicast mDNS packets into unicast packets and send them to the AC. Then the AC can record all service lists in VLAN 10, VLAN 20 and VLAN 30 and discover services across network segments.
