Reverse-path forwarding
(also RPF)
Reverse-path forwarding definition
Reverse-path forwarding is a technique in modern routers that ensures efficient packet routing and enhances network security. RPF makes sure that each internet packet takes the most direct route to its destination, prevents packet loops, and mitigates IP address spoofing attacks.
See also: multicast router
History of reverse-path forwarding
In 1982, Steve Deering first described the concept of reverse-path forwarding in a document titled “Host Extensions for IP Multicasting” as part of the Internet Engineering Task Force’s request.
In the context of IP multicasting, the reverse-path forwarding algorithm was used to build distribution trees that avoid loops and ensure that multicasts reach all hosts that have joined a specific multicast group.
In addition, RPF enhanced the security of unicast routing by preventing IP address spoofing, where a sender sends out packets with a forged source IP address. This application of RPF became increasingly important as network attacks became more prevalent with the growth of the internet.
Over the years, RPF became a part of various internet protocols and systems. This includes its use in protocols like Protocol Independent Multicast and in features like Unicast Reverse Path Forwarding implemented on routers to combat malicious activities like denial of service (DoS) attacks.