IP multicast in virtualized data centers: Challenges and opportunities

The increasing volume and importance of point-to-multipoint traffic in virtualized data centers means the deployment of IP multicast is increasingly attractive. However, concerns about the ability of switches and routers based on commodity hardware to support the conventional IP multicast control plane and data plane, especially when there are thousands of participants in the multicast group communication, results in the infrequent deployment of IP multicast in data centers. This paper discusses the evolution of data center architectures towards the virtualized architectures in which technologies such as VXLAN, VXLAN-GPE, GENEVE, STT and NVGRE are used to build emulated Layer 2 networks that will support multi-tenancy at scale. These technologies are described and compared in terms of a number of factors, with emphasis laid on the manner in which they support multicast. Lastly, innovative approaches that have been proposed to circumvent the obstacles to deploying multicast in the data center IP fabric are also discussed and evaluated.