Anti-spoofing using RPF checks

RPF is a feature with multi vendor support to prevent IP spoofing. It can be used for both unicast and multicast. RPF checks the source address of a packet as well as the interface it's being learned from. If the source address is present in the routing table, then the packet is accepted by the routing device. If not, it will drop the packet. The only problem with RPF is that it does not work with asymmetric routes and therefore requires strictly symmetric routing patterns.