Cloud-Based Networking: Development Status of NFV
Since founded in October 2012, the European Telecommunication Standards Institute Industry Specification Group for Network Functions Virtualization (ETSI ISG NFV) develops quickly, which has held six plenary sessions and includes the following works:
- Technical Steering Committee (TSC): takes charge of the overall operating of ETSI ISG NFV;
- Architecture of the Virtualization Infrastructure (AVI): takes charge of the architecture of the virtualization infrastructure;
- Management and Orchestration (MANO): takes charge of management and orchestration;
- Software Architecture (SA): takes charge of software architecture;
- Reliability and Availability (R&A): takes charge of reliability and availability;
- Performance and Portability (P&P): takes charge of performance and portability;
- Security: takes charge of security.
Especially, four overall standards, i.e., Use Cases, Architecture Framework, Terminology for Main Concepts in NFV, and Virtualization Requirements, are finalized by TSC, including five working group (WG) under TSC: Evolution and Ecosystem (EVE), Interfaces and Architecture (IFA), Testing, Experimentation, and Open Source (TST), Security (SEC), and Reliability (REL).
Compared with the current network architecture including independent business network and operation support system (OSS), NFV is deconstructed vertically and horizontally. According to NFV architecture illustrated in Fig. 2.2, from the vertical the network consists of the following three layers: NFV infrastructure (NFVI), Virtual Network Functions (VNFs), and Operation&Business Support Systems (OSS&BSS).
- NFVI is a resource pool, from the perspective of cloud computing. The mappings of NFVI on physical infrastructures are some geographically distributed data centers connected by the high-speed communication network.
- VNFs correspond with various telecommunication service networks. Each physical network element maps with a VNF. The needed resources fall into virtual computing/storage/exchange resources hosted by NFVI. Interfaces adopted by NFVI are still signaling interfaces defined by the traditional network. Moreover, it still adopts Network Element, Element Management System, and Network Management System (NE-EMS-NMS) framework as its service network management system.
- OSS&BSS is the operation support layer needing to make necessary revising and adjusting for its virtualization.
By the horizontal view, NFV includes services network and management and orchestration:
- Services network is the telecommunication service networks.
- Management and orchestration is the most significant difference between NFV and traditional network, referred to as MANO. MANO is responsible for the management and orchestration of the overall NFVI resources, business network and mapping and association of NFVI resources, and the implementation of OSS business resource process.
According to the NFV technology principle, a business network can be decomposed into a set of VNF and VNF Link (VNFL), represented as VNF Forwarding Graph (VNF-FG). Each VNF consists of several VNF Components (VNFC) and an internal connection diagram, and each VNFC is mapped to a Virtual Machine (VM).
Each VNFL corresponds to an Internet Protocol (IP) connection, which needs link resources, such as flow, Quality of Service (QoS), routing, and other parameters. Thus, the services network can make top-down dissolutions to get distributable resources through MANO. The corresponding VM resources and other resources are allocated by NFVI. In addition, the corresponding VNFL resources need to interact with the bearer network management system, and to be allocated by IP bearer network. For example, Fig. 2.3 illustrates the services network deploying NFV. According to the current technical architecture of NFV, many manufacturers have already completed the proof of concept (POC) testing and verification, such as virtual IP Multimedia Subsystem (vIMS) [1], virtualized Evolved Packet Core (vEPC) [7], virtual Customer Premise Equipment (vCPE) [8], and virtual Content Distribution Network (vCDN) [3]. And they have been demonstrated at the annual meeting of the World Radio Communication Conference (WRC) in 2014 to prove that NFV technology is available.