TOCA: A Tenant-Oriented Control Architecture for multi-domain Cloud Networks

When a cloud scales out to a large size, the cloud network potentially extends to a multi-domain structure, and needs to keep its scalability, consistency and flexibility. Software-Defined Networking (SDN) provides the technical possibility to realize the requirements. However, the existing studies of SDN focus on the perspective of network builders and managers, different from the perspective of network consumers, that will possibly cause some limitations. In this paper, we present the design of TOCA, a Tenant-Oriented Control Architecture for software-defined cloud networks. TOCA has a flat decentralized control plane structure to provide high scalability of a large-scale cloud network, in which a tenant-oriented network control mechanism is dedicated to meet the needs of consistent management in a multi-domain cloud network. Different from existing fine-gained network control method, TOCA provides abstracted network elements to describe the network communication requirements, and uses network control messages to control the network behaviors instead of the OpenFlow protocol. In this way, TOCA supports a flexible approach for tenants to define their own logical networks to meet the needs of their applications.