Cloud-Based Networking: Technical Issues of NFV

Although the criterion defined by NFC is technically feasible, there is still a long way to realize its commercial application with the following issues [4–6]:

• Maturity: Due to its too large target, only four specifications have been completed after the first phase, while many relevant specifications defined by other groups estimate to complete. Many problems have been postponed to the second phase, so there is still a long way to go to meet its mature standard.
• Compatibility: Architecture defined by NFV is quite huge with many new interfaces, dividing the closed telecom equipment manufacturers into several levels: hardware equipment suppliers, virtualization management software suppliers, virtualization software vendors, NFV Orchestrator (NFVO) software vendors, NFV system integrator, etc. Thus, the telecom network is transferred from a integration of hardware and software managed by one manufacture into a series integrations of hardware and software managed by several manufactures, so the complexity increases greatly. However, NFV only defines the architecture levels, while the detailed definition and implementation of the corresponding interfaces are to be coordinated by other technical organizations. Therefore, compared with the existing standard, the technical standards are not so strict. It is a great challenge to ensure the equipment compatibility among various manufactures in the future.
• Flexibility: The lagging Self-Organization Network (SON) technology affects

the expansion and deduction of service level. According to the NFV architecture, although the needed resources of a new VNF are automatically deployed by MANO, its business network operational architecture still relies on the traditional EMS/NMS mechanism, and the connection between VNF and traffic routing is still deployed manually and the VNF plug and play is not available. • Reliability: Traditional telecom applications often require the reliability of 99.999 %, which should not be decreased after its virtualization. Due to the special design, the reliability requirements of traditional telecom hardware are relatively high. However, the reliability of COTS equipment adopted by the virtualization is relatively lower, demanding compensation by raising the software reliability. • Integration: The current telecommunications equipment often uses special chips to realize user plane. Considering the packet mangling, x86 has lower cost performance. Therefore, its virtualization will lead to the reduction of equipment integration. Currently there are several ways to solve this problem: (1) the Software Defined Network (SDN) is implemented to separate the control and operation of user plane equipment and offload the forwarded packet to the SDN switch; (2) the Intelligent Ethernet Card including packet processing module is implemented to offload packet processing burden. • Virtualization: Compared with computing and storage virtualization, network virtualization technology is relatively backward. Although the current network virtualization technology has various types, it is a critical issue to integrate them into the NFVI. Telecommunication network is usually a distributed network needing sufficient network resources, which are decomposed to local network resource within data center, the bearer network resources among the data center, the bearer network resources between the service network and access network, etc. The allocation of the bearer network resources may involve the transport network resources allocation, which needs virtualization and automa- tion. Currently the allocation still needs to fulfil through bearer network and transport network management, which is a long way to reach the automation.2.2 Cloud Radio Access Networks 15 • Systematicity: NFV is expected to solve the problem of automatic deployment of business network, which is a giant Information and Communication Technology (ICT) integration project from the perspective of architecture. NFV can be decomposed into NFVI integration, VNF integration, and business network integration, involving a number of systems, manufactures, areas, and interfaces, which makes the engineering more difficult than the current public/private cloud. Despite its automatic deployment, every link of the telecom network deployment (planning, implementation, testing, upgrade, optimization, operations, etc.) is involved and implemented. Therefore, it is a complicated issue to implement the deployment in the future, because the technical requirement for the integrator is very high. After the implementation of NFV architecture, automatic management and agility of the telecom network should ascend dramatically. The deployment cycle of a telecommunications device is decreased from a few months to a few hours, the expansion cycle is decreased from a few weeks to a few minutes, and the new business deployment cycle of the telecommunications network is decreased from a few months to a few weeks.