Datagram Forwarding via Stateless Internetwork Switching

Virtual-circuit switching achieves high forwarding performance via the combination of a hardware frame forwarding path and link-layer connection state that is stored in each switch along a virtual circuit. A similar result can be achieved when forwarding datagrams across an internetwork by uncoupling forwarding from hop-by-hop routing. That uncoupling is achieved by using a specialized network-layer protocol to wrap the datagram of another network-layer protocol with a source route that is derived by consulting hop-by-hop routing tables. Periodically re-deriving these source routes achieves the adaptability needed to maintain compatibility with connectionless datagram routing. This paper proposes source routing as an alternative to distributed-state switching protocols for forwarding IP traffic.1