In Cisco IOS XE Bengaluru 17.5.1 and earlier releases, client packets were forwarded through the access VLAN of a client. The client also received all the IPv4 or IPv6 packets from its assigned access VLAN.

When an L3 client roamed from one controller to another controller, the point-of-presence (PoP) remained with the first controller, also known as the anchor controller or the home controller, and the point-of-attachment (PoA) moved to the second controller, also known as the foreign controller or the visited controller. In this anchor-foreign scenario, the client packets were tunneled back to the anchor controller to be forwarded on the access VLAN of the client.

Similarly, in case of L3 intracontroller roaming, when the feature Roaming Across Policy Profile is enabled, the client access VLAN is maintained, regardless of the policy profile VLAN. In such a scenario, the PoA becomes the destination policy profile VLAN.

A roaming wireless client is served better by the local services present near its PoA rather than discovering services present at its PoP. Therefore, from Cisco IOS XE Bengaluru 17.6.1 onwards, the intracontroller and intercontroller roaming scenarios described above, can now be managed with the help of the Link Local Bridging feature. Link Local Bridging is disabled by default.

If you have a local mode deployment, and L3 roaming is used to manage roaming clients across physical locations, the Link Local Bridging feature helps you to discover services, for example, using mDNS, which are physically close to the wireless client.

• The Link Local Bridging feature is supported in local-mode or FlexConnect central switching.

• Only mDNS bridge mode is supported with Link Local Bridging.

• Guest profiles are not supported.

• Wired Guest LAN, Remote LAN (RLAN), and Inter-Release Controller Mobility (IRCM) are not supported.

• Mesh and IP Source Guard (IPSG) is not supported when the Link Local Bridging feature is enabled.

• Enabling Link Local Bridging on the anchor controller and disabling it on the foreign controller is not supported, even if roaming is successful.

• Access VLAN and bridge VLAN should be operational, for the Link Local Bridging feature to work.

• Link Local Bridging must be enabled across policy profiles for the same SSID.

• Wireless multicast-over-multicast (wireless multicast multicast IP address ) must be configured, before enabling the Link Local Brigding feature. Therefore, the wireless multicast link-local command is enabled by default when wireless multicast is enabled.