A management method of IP multicast in overlay networks using openflow
Overlay networks stretch a Layer 2 network and increase mobility of virtual machines. VXLAN (Virtual eXtensible LAN) is one of Layer 2 overlay schemes over a Layer 3 net- work proposed in IETF and its definition covers 16M overlay networks or segments which solves 4K limitation of VLANs. However VXLAN uses IP multicast for the isolation of net- work traffic by tenant in the shared network infrastructure. IP multicast requires great amount of resources such as IP multicast table and CPU therefore the scalability is to be limited by handling of IP multicast. We propose to manage IP multicast in overlay networks using OpenFlow instead of using dynamic registration protocol such as IGMP. We describe our implementations of VXLAN controller, edge switch with VXLAN gateway and OpenFlow switch. Our method using OpenFlow eliminates periodical Join/Leave messages and achieves more than 4k tenants in our Layer 2 network at server edges, which was not possible before.