Table of Content

    25 June 2014, Volume 12 Issue 2
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    The whole issue of ZTE Communications June 2014, Vol. 12 No. 2
    2014, 12(2):  0. 
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    Special Topic
    Guest Editorial: Software-Defined Networking
    Zhili Sun, Jiandong Li, and Kun Yang
    2014, 12(2):  1-2. 
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    Software - defined networking (SDN) is a promising technology for next-generation networking and has attracted much attention from academics, network equipment manufacturer, network operators, and service providers. It has found applications in mobile, data center, and enterprise networks. The SDN architecture has a centralized, programmable control plane that is separate from the data plane. SDN also provides the ability to control and manage virtualized resources and networks without requiring new hardware technologies. This is a major shift in networking technologies.
    The ITU-T has been engaged in SDN standardization, and the European Telecommunications Standard Institute (ETSI) has been working on network function virtualization (NFV), which complements SDN. The Open Network Foundation (ONF) is a non-profit organization dedicated to promoting the adoption of open SDN. Recently, much work has been done on SDN to meet future network requirements.
    Network virtualization creates multiple virtual infrastructures within a deployed infrastructure. These virtualized infrastructures can be created over a single physical infrastructure. Each virtual network can be isolated from each other and programmed to meet user requirements in terms of resource functionality and capacity. This ensures that appropriate network resources are provided to the user.
    The SDN framework includes programmable control plane, data-forwarding plane abstraction, and methods to map the virtualized infrastructures onto the underlying physical network infrastructure.
    Key issues to be addressed are network resource isolation, network abstraction, topology awareness, quick reconfigurability, performance, programmability, management, mobility, security, and wireless network access.
    We received strong response to this call for papers on SDN from network operators, equipment manufacturers, universities, and research institutes. Following a peer-review process, we selected nine papers for inclusion in this special issue.
    The first paper,“Network Function Virtualization Technology: Progess and Standardization”discusses the main challenges in SDN faced by network carriers. This paper also discusses current standardization activities and research on NFV related to SDN.
    The second paper,“Service Parameter Exposure and Dynamic Service Negotiation in SDN Environments,”discusses the ability of SDN to facilitate dynamic provisioning of network services. The paper focuses on two main aspects of the SDN framework: network abstraction and dynamic parameter exposure and negotiation.
    The third paper,“SDN-Based Broadband Network for Cloud Services,”discusses how SDN/NFV will be vital for constructing cloud-oriented broadband infrastructure, especially within data center networks and for interconnecting between data center networks. The authors propose SDN/NFV in broadband access to realize a virtualized residential gateway.
    The fourth paper,“D-ZENIC: A Scalable Distributed SDN Controller Architecture,”describes a solution to minimizing the cost of network state distribution. This solution is a network control platform called D-ZNEIC that supports distributed deployment and linear scale-out by trading off complexity for scalability.
    The fifth paper,“Software-Defined Cellular Mobile Network Solutions,”describes current research on and solutions for software-defined cellular networks. It also discusses related specifications and possible research directions.
    The sixth paper,“SDN-Based Data Offloading for 5G Mobile Networks,”describes an integrated 4G/Wi-Fi architecture evolved with SDN abstraction in the mobile backhaul and enhanced components that facilitate the move towards 5G.
    The seventh paper,“Integrating IPsec Within OpenFlow Architecture for Secure Group Communication,”discusses Internet Protocol security (IPsec) in the context of OpenFlow architecture and SDN.
    The eighth paper,“Virtualized Wireless SDNs: Modelling Delay Through the Use of Stochastic Network Calculus,”describes a delay model for a software-defined wireless virtual network with some theoretical investigation into wireless SDN.
    The final paper,“Load Balancing Fat-Tree on Long-Lived Flows: Avoiding Congestions in Data Center Network,”describes a dynamic load-balancing algorithm for fat tree in the context of SDN architecture.
    Network Function Virtualization Technology: Progress and Standardization
    Huiling Zhao, Yunpeng Xie, and Fan Shi
    2014, 12(2):  3-7.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.001
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    Network innovation and business transformation are both necessary for telecom operators to adapt to new situations, but operators face challenges in terms of network bearer complexity, business centralization, and IT/CT integration. Network function virtualization (NFV) may inspire new development ideas, but many doubts still exist within industry, especially about how to introduce NFV into an operator’s network. This article describes the latest progress in NFV standardization, NFV requirements and hot technology issues, and typical NFV applications in an operator networks.
    Service Parameter Exposure and Dynamic Service Negotiation in SDN Environments
    M. Boucadair and C. Jacquenet
    2014, 12(2):  8-17.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.002
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    Software-defined networking (SDN) is a generic term and one of the major interests of the telecoms industry (and beyond) over the past two years. However, defining SDN is a somewhat controversial exercise. The claimed flexibility, as well as other presumed assets of SDN, should be carefully investigated. In particular, the use of SDN to dynamically provision network services suggests the introduction of a certain level of automation in the overall network service delivery process, from service parameter negotiation to delivery and operation. This paper aims to clarify the SDN landscape and focuses on two main aspects of the SDN framework: network abstraction, and dynamic parameter exposure and negotiation.
    SDN-Based Broadband Network for Cloud Services
    Xiongyan Tang, Pei Zhang, and Chang Cao
    2014, 12(2):  18-22.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.003
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    Over-the-top services and cloud services have created great challenges for telecom operators. To better meet the requirements of cloud services, we propose a decoupled network architecture. Software-defined networking/network function virtualization (SDN/ NFV) will be vital in the construction of cloud-oriented broadband infrastructure, especially within data centers and for interconnection between data centers. We also propose introducing SDN/NFV in the broadband access network in order to realize a virtualized residential gateway (VRG). We discuss the deployment modes of VRG.
    D-ZENIC: A Scalable Distributed SDN Controller Architecture
    Yongsheng Hu, Tian Tian, and Jun Wang
    2014, 12(2):  23-27.  doi:DOI:10.3939/j.issn.1673-5188.2014.02.004
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    In a software-defined network, a powerful central controller provides a flexible platform for defining network traffic through the use of software. When SDN is used in a large-scale network, the logical central controller comprises multiple physical servers, and multiple controllers must act as one to provide transparent control logic to network applications and devices. The challenge is to minimize the cost of network state distribution. To this end, we propose Distributed ZTE Elastic Network Intelligent Controller (DZENIC), a network-control platform that supports distributed deployment and linear scale-out. A dedicated component in the DZENIC controller provides a global view of the network topology as well as the distribution of host information. The evaluation shows that balance complexity with scalability, the network state distribution needs to be strictly classified.
    Software-Defined Cellular Mobile Network Solutions
    Jiandong Li, Peng Liu, and Hongyan Li
    2014, 12(2):  28-33.  doi:DOI:10.3939/j.issn.1673-5188.2014.02.005
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    The emergency relating to software-defined networking (SDN), especially in terms of the prototype associated with OpenFlow, provides new possibilities for innovating on network design. Researchers have started to extend SDN to cellular networks. Such new programmable architecture is beneficial to the evolution of mobile networks and allows operators to provide better services. The typical cellular network comprises radio access network (RAN) and core network (CN); hence, the technique roadmap diverges in two ways. In this paper, we investigate SoftRAN, the latest SDN solution for RAN, and SoftCell and MobileFlow, the latest solutions for CN. We also define a series of control functions for CROWD. Unlike in the other literature, we emphasize only softwaredefined cellular network solutions and specifications in order to provide possible research directions.
    SDN-Based Data Offloading for 5G Mobile Networks
    Mojdeh Amani, Toktam Mahmoodi, Mallikarjun Tatipamula, and Hamid Aghvami
    2014, 12(2):  34-40.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.006
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    The rapid growth of 3G/4G enabled devices such as smartphones and tablets in large numbers has created increased demand for mobile data services. Wi-Fi offloading helps satisfy the requirements of data-rich applications and terminals with improved multimedia. Wi-Fi is an essential approach to alleviating mobile data traffic load on a cellular network because it provides extra capacity and improves overall performance. In this paper, we propose an integrated LTE/Wi-Fi architecture with software-defined networking (SDN) abstraction in mobile backhaul and enhanced components that facilitate the move towards next-generation 5G mobile networks. Our proposed architecture enables programmable offloading policies that take into account real-time network conditions as well as the status of devices and applications. This mechanism improves overall network performance by deriving realtime policies and steering traffic between cellular and Wi-Fi networks more efficiently.
    Integrating IPsec within OpenFlow Architecture for Secure Group Communication
    Vahid Heydari Fami Tafreshi, Ebrahim Ghazisaeedi, Haitham Cruickshank, and Zhili Sun
    2014, 12(2):  41-49.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.007
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    Network security protocols such as IPsec have been used for many years to ensure robust end-to-end communication and are important in the context of SDN. Despite the widespread installation of IPsec to date, per-packet protection offered by the protocol is not very compatible with OpenFlow and flow-like behavior. OpenFlow architecture cannot aggregate IPsec-ESP flows in transport mode or tunnel mode because layer-3 information is encrypted and therefore unreadable. In this paper, we propose using the Security Parameter Index (SPI) of IPsec within the OpenFlow architecture to identify and direct IPsec flows. This enables IPsec to conform to the packet-based behavior of OpenFlow architecture. In addition, by distinguishing between IPsec flows, the architecture is particularly suited to secure group communication.
    VirtualizedWireless SDNs: Modelling Delay Through the Use of Stochastic Network Calculus
    Lianming Zhang, Jia Liu, and Kun Yang
    2014, 12(2):  50-56.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.008
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    Software-defined networks (SDN) have attracted much attention recently because of their flexibility in terms of network management. Increasingly, SDN is being introduced into wireless networks to form wireless SDN. One enabling technology for wireless SDN is network virtualization, which logically divides one wireless network element, such as a base station, into multiple slices, and each slice serving as a standalone virtual BS. In this way, one physical mobile wireless network can be partitioned into multiple virtual networks in a software-defined manner. Wireless virtual networks comprising virtual base stations also need to provide QoS to mobile end-user services in the same context as their physical hosting networks. One key QoS parameter is delay. This paper presents a delay model for software-defined wireless virtual networks. Network calculus is used in the modelling. In particular, stochastic network calculus, which describes more realistic models than deterministic network calculus, is used. The model enables theoretical investigation of wireless SDN, which is largely dominated by either algorithms or prototype implementations.
    Load Balancing Fat-Tree on Long-Lived Flows: Avoiding Congestion in a Data Center Network
    Wen Gao, Xuyan Li, Boyang Zhou, and Chunming Wu
    2014, 12(2):  57-62.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.009
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    In a data center network (DCN), load balancing is required when servers transfer data on the same path. This is necessary to avoid congestion. Load balancing is challenged by the dynamic transferral of demands and complex routing control. Because of the distributed nature of a traditional network, previous research on load balancing has mostly focused on improving the performance of the local network; thus, the load has not been optimally balanced across the entire network. In this paper, we propose a novel dynamic load-balancing algorithm for fat-tree. This algorithm avoids congestions to the great possible extent by searching for non-conflicting paths in a centralized way. We implement the algorithm in the popular software-defined networking architecture and evaluate the algorithm’s performance on the Mininet platform. The results show that our algorithm has higher bisection bandwidth than the traditional equal-cost multi-path load-balancing algorithm and thus more effectively avoids congestion.
    Research Paper
    Formal Protection Architecture for Cloud Computing System
    Yasha Chen, Jianpeng Zhao, Junmao Zhu, and Fei Yan
    2014, 12(2):  63-66.  doi:DOI:10.3969/j.issn.1673-5188.2014.02.010
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    Cloud computing systems play a vital role in national security. This paper describes a conceptual framework called dualsystem architecture for protecting computing environments. While attempting to be logical and rigorous, formalism method is avoided and this paper chooses algebra Communication Sequential Process.