Mobile Internet is an integral part of daily life and the development of the world. The delay of mobile Internet directly affects the income of enterprises that provide Internet services and our living standards. According to research, DNS is one of the two most important factors affecting Internet latency. DNS relies on extensive caching for good performance. Additionally, each DNS zone provides caching to improve DNS response speed, but most caching is recursive. In terms of authoritative caching, except for the root cache, the caches of other tlds are less concerned. This paper analyzes the impact of domestically deployed .com and .net caches on resolution time, hoping to find out the impact of tld cache on DNS resolution speed. To this end, we have an online deployment at China Mobile Communications Group Henan Co., Ltd. A large number of experimental results show that the tld cache can greatly improve the DNS resolution speed and reduce the Internet delay.

Abstract Domain Name System (DNS) is a key infrastructure on the Internet. The Distribution Master (DM) system is used to transmit root zone data from Internet Assigned Numbers Authority (IANA) to the root server. DM is a centralized system that will introduce single points of failure and abuse of authority. To solve the problem of a single point of failure, we adopt the decentralization of blockchain in architecture, and propose a blockchain-based distributed DM architecture, which allows nodes to join and exit at any time. At the technical level, the 3R-PBFT (Replicated, Redundant Practical Byzantine Fault Tolerance) algorithm is proposed to reach a consensus, which increases the security of the system. We use flexible mechanisms to reduce the number of signatures and improve the performance of the system. A threshold signature algorithm is used to ensure the uniqueness of the signature key information, and the increase of DM nodes will not bring about an increase in the number of keys. The advantages of the system structure in stability and scalability were verified by experiments.

Summary The cyber‐physical system (CPS) has become a promising direction that can enrich the interaction between people and people, people and objects, objects and objects in the physical world and the virtual world. Because of the development of CPS, the number and types of smart device connected to the Internet has rapidly increased, bringing with it the current issues of flexibility, efficiency, availability, security, and scalability of the Internet‐of‐Things (IoT) network. These problems are caused by the key mechanism of large‐scale distribution to the IoT network. In this article, we propose CPSS inspired by software‐defined networking (SDN) and service‐oriented architecture, which is a powerful software‐defined cyber‐physical system to solve the challenges of broader CPS adoption. CPSS has three complementary modules: application‐as‐a‐service (AAAS), network‐as‐a‐service (NAAS), and infrastructure‐as‐a‐service (IAAS). IAAS collects network information from a different set of controllers and devices and generates a domain‐wide network view. NAAS collects information from different domains and generates a global view, which helps data transmission between different domains and enables seamless switching between applications and infrastructure devices. AAAS provides personalized service for each user. To test CPSS, we develop a prototype system. Our experimental results show that CPSS can effectively control cyber‐physical system, and CPSS has greatly improved network latency, network throughput, and network reliability compared to traditional controller‐controlled CPS.

In software-defined network, the use of distributed controllers to control forwarding devices has been proposed to solve the issues of scalability and load balance. However, the forwarding devices are statically assigned to the controllers in these distributed systems, which can overload some controllers while others are underutilized. In this paper, we propose an architecture named ASLB (active controller selection load balance), which proactively selects appropriate controllers for load balancing and minimize packet processing delays. We also present a novel active controller selection algorithm (ACS) for ASLB that efficiently schedules traffic from the switch to the controller and designs an intermediate coordinator for actively selecting a controller to serve a request. We built a system and evaluated it on a physical platform. The results show that ASLB is much better than the static allocation scheme in terms of minimizing latency, bandwidth utilization, and throughput.

As a novel architecture, software-defined networking (SDN) is viewed as the key technology of future networking. The core idea of SDN is to decouple the control plane and the data plane, enabling centralized, flexible, and programmable network control. Although local area networks like data center networks have benefited from SDN, it is still a problem to deploy SDN in wide area networks (WANs) or large-scale networks. Existing works show that multiple controllers are required in WANs with each covering one small SDN domain. However, the problems of SDN domain partition and controller placement should be further addressed. Therefore, we propose the spectral clustering based partition and placement algorithms, by which we can partition a large network into several small SDN domains efficiently and effectively. In our algorithms, the matrix perturbation theory and eigengap are used to discover the stability of SDN domains and decide the optimal number of SDN domains automatically. To evaluate our algorithms, we develop a new experimental framework with the Internet2 topology and other available WAN topologies. The results show the effectiveness of our algorithm for the SDN domain partition and controller placement problems.

Traditional networks are surprisingly fragile and difficult to manage. Software Defined Networking (SDN) gained significant attention from both academia and industry, as if simplify network management through centralized configuration. Existing work primarily focuses on networks of limited scope such as data-centers and enterprises, which makes the development of SDN hindered when it comes to large-scale network environments. One way of enabling communication between data-centers, enterprises and ISPs in a large-scale network is to establish a standard communication mechanism between these entities. In this paper, we propose Zebra, a framework for enabling communication between different SDN domains. Zebra has two modules: Heterogeneous Controller Management (HCM) module and Domain Relationships Management (DRM) module. HCM collects network information from a group of controllers with no interconnection and generate a domain-wide network view. DRM collects network information from other domains to generate a global-wide network view. Moreover, HCM supports different SDN controllers, such as floodlight, maestro and so on. To test this framework, we develop a prototype system, and give some experimental results.