ROME: Routing on metropolitan-scale Ethernet

We present the architecture and protocols of ROME, a layer-2 network designed to be backwards compatible with Ethernet and scalable to tens of thousands of switches and millions of end hosts. ROME is based upon a recently developed geographic routing protocol, greedy distance vector (GDV). Switches in ROME do not need any location information. Protocol design innovations in ROME include a stateless multicast protocol, a Delaunay DHT, as well as routing and host discovery protocols for a hierarchical network. ROME protocols do not use broadcast. Extensive experimental results from a packet-level event-driven simulator, in which ROME protocols are implemented in detail, show that ROME protocols are efficient and scalable to metropolitan size. Furthermore, ROME protocols are highly resilient to network dynamics. The routing latency of ROME is only slightly higher than shortest-path latency. To demonstrate scalability, we provide simulation performance results for ROME networks with up to 25,000 switches and 1.25 million hosts.