SAVE. The Source Address Validity Enforcement protocol, or SAVE
[Li et al. 2002], while not designed with DPF in mind, operates similarly in
that routers filter packets based on their incoming direction. Whereas the original
DPF work did not provide a means of discovering valid incoming direction
knowledge (DPF simply assumes routers have that knowledge), SAVE is the
first protocol that helps routers learn the information and leverage the knowledge
for filtering spoofing packets.