To migrate the gateway address out of the ACI fabric for an endpoint group (EPG), the bridge domain configuration must ensure that routing is contained within the ACI fabric and that ARP requests are managed efficiently. The correct configuration set is:

L2 Unknown Unicast: Set to Hardware Proxy. This setting allows the ACI fabric to use the spine proxy function to handle unknown unicast traffic, which helps to reduce flooding within the fabric.

Unicast Routing: Set to Disabled. Since the gateway is being migrated out of the ACI fabric, unicast routing should be disabled to prevent the ACI fabric from attempting to route traffic for the EPG.

ARP Flooding: Set to Enabled. This allows ARP requests to be flooded within the bridge domain, which is necessary when the unicast routing is disabled, to ensure that ARP requests can still be resolved.

References :=

Cisco ACI Bridge Domain Configuration Guide

Cisco ACI Best Practices Guide