Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE Bengaluru 17.6.x

From Cisco IOS XE Amsterdam 17.2.1, Multichassis Link Aggregation Group (multi-LAG), which provides flexibility in connecting the controller to a switch's infrastructure is supported. Using multi-LAG, you can connect the multiple uplinks from the controller to the separated uplink switches. The controller supports VLAN-based traffic splitting when connected to a multiswitch topology. This provides the ability to distribute traffic on different uplinks, based on VLANs, for example, supporting a use case where guest traffic can be completely isolated to a different switch or network from the enterprise network. Same VLAN cannot be configured on both the uplinks.

You can connect a LAG to a single switch. However, different VLANs must be connected to different LAGs. The redundancy port must be connected to the same distribution switch as the uplinks, or back to back.

Multi-LAG is supported in LAG ON mode, LACP, and PAgP modes.