Flow management and orchestration for virtualized network functions in software-defined networks

This chapter discusses network function virtualization (NFV) to enhance flexibility and reduce costs in the deployment of service networks. NFV utilizes virtualization (e.g., virtual machines (VMs)) to separate network functions (NFs) from hardware in the form of virtual network functions (VNFs), for placement within general-purpose host machines. This makes it possible for network operators to serve a larger number of users and meet service level agreements (SLAs). This necessitates the intelligent management ofVNFs and the flowamong them. Software-defined networking (SDN) is ideal for this, because the separation of control and data planes makes it possible to centralize network operations. To better understand the concept of Network as a Service (NaaS), this chapter describes how NFV works with SDN, and how the flow among service chains of VNFs in SDN networks can be managed.We outline issues crucial to the design of networks from various perspectives using a number of performance metrics. Experimental results illustrate how SLA affects network performance in NFV with SDNs. Thus, flow management for service chains of VNFs in SDNs is also covered. Two categories of orchestration mechanism in the control plane are introduced: single flow and multiple flow. We discuss latency and throughput-aware algorithms for flow management and study the problem of resource contention in datacenter networks. Finally, a summary is provided to indicate directions for future research.