SUBMARINE: an architecture for IP routing over large NBMA networks

As communications networks grow in both speed and scale, there is a need to switch packets at higher speeds. One approach is to use fast switches that operate at the datalink layer (layer 2) to build a high-performance “cloud” for interconnecting network layer routers. The use of ATM for the layer 2 network provides a number of advantages when the network is shared among multiple services and when additional capabilities that are supported well at layer 2, such as fine-grained per-flow QoS, are needed. This paper describes a robust and efficient solution to the problem of supporting IP over a large non-broadcast multiple-access (NBMA) network, such as ATM. The solution, known as SUBMARINE, calculates loop-free shortcut routes across the NBMA network. SUBMARINE builds on existing IP routing protocols, is designed to scale to multiple areas within a single autonomous system, and makes minimal changes to the IP forwarding process