A concept of “Interface Class” is introduced. All logical interfaces that belong to an Interface Class are indistinguishable in hardware. Each Interface Class is associated with one or more packet forwarding rules, such as Access Control Lists (ACLs), Policy Routes, and Quality of Service (QoS)....http://www.google.com/patents/US7466698?utm_source=gb-gplus-sharePatent US7466698 - Network node with layer 3 interfaces configurable by interface class
