Applying NFV and SDN to LTE mobile core gateways, the functions placement problem

Abstract

With the rapid growth of user data, service innovation, and the persistent necessity to reduce costs, today's mobile operators are faced with severe challenges. In networking, two new concepts have emerged aiming at cost reduction, increase of network scalability and service flexibility, namely Network Functions Virtualization (NFV) and Software Defined Networking (SDN). NFV proposes to run the mobile network functions as software instances on commodity servers or datacenters (DC), while SDN supports a decomposition of the mobile network into control-plane and data-plane functions. Whereas these new concepts are considered as very promising drivers to design cost efficient mobile network architectures, limited attention has been drawn to the network load and infringed data-plane delay imposed by introducing NFV or SDN. We argue that within a widely-spanned mobile network, there is in fact a high potential to combine both concepts. Taking load and delay into account, there will be areas of the mobile network rather benefiting from an NFV deployment with all functions virtualized, while for other areas, an SDN deployment with functions decomposition is more advantageous. We refer to this problem as the functions placement problem. We propose a model that resolves the functions placement and aims at minimizing the transport network load overhead against several parameters such as data-plane delay, number of potential datacenters and SDN control overhead. We illustrate our proposed concept along with a concrete use case example.

Model for Efficient Allocation of Network Functions in Hybrid Environment

“…This phenomenon has encouraged mobile network operators to build complex network architectures by incorporating new features and extensions, which are harder to manage and operate [1]. Two concepts are in the focus of research and development at the moment -Network Functions Virtualization (NFV) and Software Defined Networking (SDN) [2].…”

“…Dynamic network instantiation is seen as an important tool to cope with the rapid change of services and users behavior. Therefore, it is expected that NFV would have an impact on the desired cost reduction in today's mobile networks [2].…”

“…SDN introduces what is called Network Functions Decomposition (NFD), where control-plane functions would be appended to a logically centralized controller that could be deployed in a datacenter platform, while data-plane functions are realized by SDN networking elements at the transport network [2].…”

“…In the last years, many scientific contributions [22] addressed the virtual network embedding problem, either applying mathematical optimization models (e.g. [2], [11], [23]) or algorithmic approaches (e.g. [24]).…”

“…In the study [2] the optimal virtualized gateways placement is considered as well as the problem of virtualization and SDN decomposition deployment on the mobile core gateways. However, the placement problem also arises for other network functions.…”