• Unicast mode end points • Unicast mode Layer 2 network End Points for Unicast Mode Starting with Cisco IOS XE Amsterdam Release 17.3.2, Cisco Catalyst 9000 Series switches and Cisco Catalyst 9800 Series WLCs introduce Layer 2 unicast service gateway solution. The mDNS endpoint continues to advertise or query services over Layer 2 mDNS. However, with the unicast mode settings enabled, the incoming mDNS IPv4 and IPv6 frames are handled uniquely. The unicast technique eliminates the mDNS flood challenges and provides a policy-based service query response to the requesting end points over a unicast MAC address.
The following figure illustrates the functional difference between the new Layer 2 unicast (flood-free) and the traditional Layer 2 Multicast (flood) communication with wired and wireless end points. Figure 1: Layer 2 Unicast Mode End Points Layer 2 Network for Unicast Mode The Layer 3 boundary for wired and wireless networks can reside in the distribution layer with Layer 2 connections extended over trunk ports to an access layer switch or WLC. The association of the nonpruned or common VLAN ID to the trunk ports extends the Layer 2 flood boundary across the network.
Starting with Cisco IOS XE Amsterdam Release 17.3.2, Cisco Catalyst 9000 Series switches and Cisco Catalyst 9800 Series WLCs introduce the Service Peer role to eliminate transmitting mDNS flood over trunk ports. The Service Peer establishes a unicast Layer 3 IPv4-based service-routing session with the distribution layer system in Service Discovery Gateway (SDG) role. The Service Peer establishes the session over the existing Layer 2 trunk ports without modifying any existing Layer 2 VLAN configuration.
The new mDNS trust port between access layer and distribution layer uses the existing out-of-band management network to statefully discover and distribute services (based on policies) to replace traditional flood-n-learn methods from the Layer 2 network. If the Layer 3 boundary in a LAN environment is at the access layer, then the SDG mode provides integrated Service Peer role. Further, the SDG mode needs only Wide Area Bonjour with Cisco Catalyst Center for service-routing in a Layer 3 IP network. The following figure illustrates a Layer 2 Network with the unicast mode and a traditional Layer 2 network with mDNS flood:
Configuring Local Area Bonjour in Unicast Mode for LAN Networks End Points for Unicast Mode Configuring Local Area Bonjour in Unicast Mode for LAN Networks 3