Flow Labelled IP: A Connectionless Approach to ATM

Peter Newman, Tom Lyon, and Greg Minshall

To be presented at IEEE Infocom, March 1996, Session 10B, Thursday March 28 1:30pm.

A number of proposals for supporting IP over ATM are under discussion in the networking community including: LAN emulation, classical IP over ATM, routing over large clouds, and multiprotocol over ATM. Each of these proposals hides the real network topology from the IP layer by treating the data link layer as a large, opaque, network cloud. We argue that this leads to complexity, inefficiency and duplication of functionality in the resulting network.

We propose an alternative in which we discard the connection oriented nature of ATM and integrate fast ATM hardware directly with IP, preserving the connectionless nature of IP. We use "soft" state in the ATM hardware to cache the IP forwarding decision. This enables further traffic on the same IP flow to be switched by the ATM hardware rather than forwarded by IP software. We claim that this approach combines the simplicity, scalability, and robustness of IP with the speed, capacity, and multiservice traffic capabilities of ATM.