Lcast: Software-defined inter-domain multicast
Traditionally, efficient inter-domain data delivery may be implemented either as a network or as an application layer multicast service. However, while the former has seen little uptake due to prohibitive deployment costs the latter is widely used today, but often without a minimum guaranteed performance. In this paper we present Lcast, a network-layer single-source multicast framework designed to merge the robustness and efficiency of IP multicast with the configurability and low deployment cost of application-layer overlays. The architecture involves no end-host changes and only requires the upgrading of a small set of routers to support the Locator/ID Separation Protocol (LISP), an incrementally deployable enhancement to the current global routing infrastructure. Content distribution over the Internet's core is done by means of a router overlay while within domains, end-hosts interface with Lcast using conventional multicast protocols. The overlay's scalability and topological configurability is sustained by logically centralizing group management. We illustrate the versatility of our solution by designing and assessing the scalability and performance of three management strategies for low latency content distribution. Our analysis is based on large scale simulations supported by realistic user behavior and Internet-like network topologies. The results show Lcast's low management overhead and ability to optimize delivery to meet various operational constraints. Notably, we find that it can deliver traffic with latencies close to unicast ones, independent of overlay size.