When symmetric mobility tunneling is enabled, all client traffic is sent to the anchor controller and can then successfully pass the RPF check.
Figure 1. Symmetric Mobility Tunneling or Bi-Directional Tunneling
Symmetric mobility tunneling is also useful in the following situations:
If a firewall installation in the client packet path drops packets because the source IP address does not match the subnet on which the packets are received.
If the access-point group VLAN on the anchor controller is different than the WLAN interface VLAN on the foreign controller. In this case, client traffic could be sent on an incorrect VLAN during mobility events.