Network function virtualization in the multi-tenant cloud

With more and more tenants launching their applications on the cloud, various requirements have been posed regarding the cloud's performance, security, and management. In the face of tenant demands, the cloud provider deploys different hardware middleboxes, carrying out different network functions, and enhancing the cloud's capability in serving tenant requirements. While middleboxes are crucial to the cloud, concerns have been raised regarding their costs, manageability, and performance overhead. To tackle these problems, researchers have proposed an alternative to hardware middleboxes: network function virtualization. Software applications are deployed in place of hardware middleboxes, offering equivalent functionalities while greatly improving flexibility, manageability, and cost-efficiency. In this paper we discuss opportunities and challenges that network function virtualization brings to the multi-tenant cloud. We also propose a cloud architecture that exploits virtual network functions. Our contributions can serve as an enlightener for future efforts in this area.