1-When the packet in ACI comes into leaf switch is L3 based, in the beginning the leaf will check the destination IP address for End Point (Dst IP).
2-If the leaf switch already knows the destination IP address, the leaf switch will send the packet to local port (if destination IP on the same leaf) or to remote leaf (if destination IP is not in the same leaf leaf).
3-If leaf switch doesn‘t know the destination IP address for end point, the leaf will immediately check its routing table to see if it has BD subnet for that destination IP in its routing table.
4-When subnet of BD is existing, ingress leaf will directly send this packet to Spine Proxy. Then, Spine Proxy will check its COOP database and will forward the packet to remote leaf or start with ARP glean (if destination IP is not in COOP database).
5- Finally, If BD subnet is not existing in the routing table, the leaf switch will directly searches for any other entry in routing table. If there is a L3Out route the ingress leaf will immediately send the packet to appropriate border leaf. If there isn‘t any route in the routing table, ingress leaf will drop the packet.
