3. Challenges of Traditional Networks and Development of Programmable Networks

The life cycle of a network system usually includes four stages: demand investigation, planning and design, deployment and implementation, and operation and maintenance. Based on this cycle, a huge network architecture has now been formed, which has played an important role in promoting economic and social development. However, with the vigorous rise of technologies such as big data, cloud computing, Internet of Things, and mobile Internet, Internet applications are becoming increasingly diversified and business volume is increasing. Therefore, the current network architecture is gradually unable to meet the demand, and the existing problems are becoming increasingly prominent. In general, the core problem is that there is a contradiction between the diverse and changeable network upper-layer applications and business requirements and the current stable and rigid traditional network architecture. In order to meet a specific application requirement, it usually needs to include a large number of hardware devices. However, a noteworthy problem is that network devices produced by different manufacturers usually require different ways to debug and configure. Therefore, in a network that mixes equipment from multiple different vendors, managing and deploying the network is a very big challenge. Moreover, the inability to perform intelligent flow control and visualized network status supervision based on network conditions is also a problem that hinders further development. Based on the above problems, software-defined networking (SDN) is a better solution. In general, SDN has the following three advantages: (1) SDN can change the tightly coupled architecture of applications and networks under traditional networks and improve the level of network resource pooling; (2) SDN networks can realize automatic network deployment and configuration, and support rapid business launch and flexible expansion; (3) By introducing programmable features, automated network services and protocol scheduling can be realized. However, the architecture still has some challenges worth considering, such as: (1) Challenges faced by interface/protocol standardization. At present, the control architecture system of the SDN centralized control concept is not unified, and it is difficult to achieve mutual operation due to the different degrees of vendors’ support for the SDN standard. (2) Security challenges. The core controller of the SDN network may have security problems such as excessive load, single point failure, and vulnerability to network attacks. Therefore, it is necessary to establish a reasonable mechanism to ensure the safe and stable operation of the entire system. (3) Challenges in performance. The existing ASIC chip architecture is based on the traditional IP or Ethernet addressing and forwarding design. Therefore, whether the equipment under the SDN architecture can maintain the theoretical high performance remains to be discussed. To sum up, this chapter will start from the analysis and comparison of the traditional network architecture and the SDN network architecture, summarize the problems in the traditional architecture and the necessity of the development of the SDN architecture, and further analyze the application scenarios and the existence of the SDN architecture challenge.