IDPF. Inter-Domain Packet Filters, or IDPF [Duan et al. 2006], attempts
to provide an implementation of the DPF principles. Learning from
BGP updates, and assuming that BGP routers adhere to a specific set of exporting
rules, routers running IDPF can discover AS relationship information
and then use this information to build packet filtering rules. In general, ASes
can be in a provider-customer, peer-peer, or sibling-sibling relationship. These
relationships put constraints on which AS paths are feasible, and which are
not feasible. Packets which arrive from neighbors along an infeasible path can
be filtered out.