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Verifiable databases (VDB) enables the data owner to outsource a huge unencrypted database to the powerful but untrusted cloud such that any client could later retrieve the database and check whether the cloud returns valid records or not. To the best of our knowledge, there is no prior work considering privacy. Besides, they assume that the data owner and the client are fully trusted while they may be semi-honest in the real world. To address these problems, we propose a new primitive called privacy-preserving publicly verifiable database (PPVDB), which not only guarantees the integrity of the query result but also leaks no information. At the end of this protocol, the client can check whether the cloud returns a valid result and learns the query result but nothing else about the database. Besides, the cloud learns nothing about the database and the query, and the data owner does not know which item that the client has queried. Motivated by the comparison among some strawman solutions, we incorporate verifiable computation for the polynomial with oblivious pseudorandom function to construct a PPVDB scheme, which is the first VDB scheme providing stronger security against the malicious cloud and the semi-honest client and data owner.

Network Calculus is an established analytical framework which can provide deterministic estimates of latency and buffer requirements for feed-forward packet-switched communication networks. Researchers find it useful in analyzing network performance in real-time systems. As there are several Network Calculus tools and software packages for estimating network performance, it is important to select suitable Network Calculus tools for network analysis problems. This article introduces twelve established tools for Network Calculus analysis and compares their advantages and disadvantages in terms of their applicability for various systems and analysis needs. We also provide recommendations for users to select the suitable tools for research. Five public tools, namely DiscoDNC, RTC Toolbox, Deborah, CyNC, and nc-tandem-tight, are chosen to analyze end-to-end delay in a series of tandem networks for their performance demonstration. Simulations of the same tandem networks are implemented to compare with the analytical results achieved by the Network Calculus tools. To our best knowledge, this is the first comprehensive study that compares existing tools of Network Calculus analysis for real-time system network infrastructure. Our aim is to provide quick guidance to research communities for selecting suitable tools to analyze delay performance of networks.

Network function virtualization (NFV), has been widely adopted in existing networks since it brings lower capital expenditure and operating expense, as well as flexible and elastic deployment. Based on NFV, dynamic Service function chain (SFC) provides more comprehensive and thorough traffic steering over a series of middleboxes, e.g., DPI, and IDS. Nevertheless, dynamic SFC involves internal state migration in middleboxes, making it hard to allocate SFC requests. We propose a reconfigurable SFC scheduling approach with consideration on resource constraints and race of the state migration to collaborate the execution of the SFC reconfiguration, in the reasonable fashion based on a heuristic algorithm. The evaluation is conducted through discrete event simulation to validate the efficiency of our reconfigurable SFC scheduling, and the results demonstrate that the proposed method outperforms First Come First Serve scheduling and random scheduling.

In electrical transmission grids, the redundant communication paths nondisjointly overlapping at links can be established between certain substations and the control center to guarantee reliable packet delivery under link failures. However, the generation of nondisjoint paths with multiplicative and concave constraints is with the NP-complete complexity and the failovers can lead to out-of-order packets. This paper presents an OpenFlow-based nondisjoint path aggregation mechanism to heuristically compute the constrained nondisjoint paths in a centralized fashion and reorganize the out-of-order packets at edge switches. The solution is evaluated through simulations of the IEEE 30-bus network scenario under 2% link failure rate and the result confirms its effectiveness: the packet delivery success rate is significantly improved in comparison with the current nondisjoint and disjoint path algorithms. TCP throughput is improved by 121.62% with the packet reordering. Also, the memory usage for the packet reordering buffer is reduced by 76.563% compared with the distributed cognitive packet network.

When applying Software-Defined Networks (SDN) to WANs, the SDN flexibility enables the cross-domain control to achieve a better control scalability. However, the control consistence is required by all the cross-domain services, to ensure the data plane configured in consensus for different domains. Such consistence process is complicated by potential failure and errors of WANs. In this paper, we propose a consistence layer to actively and passively snapshot the cross-domain control states, to reduce the complexities of service realizations. We implement the layer and evaluate performance in the PlanetLab testbed for the WAN emulation. The testbed conditions are extremely enlarged comparing to the real network. The results show its scalability, reliability and responsiveness in dealing with the control dynamics. In the normalized results, the active and passive snapshots are executed with the mean times of 1.873s and 105ms in 135 controllers, indicating its readiness to be used in the real network.

In the Software-defined networking (SDN), when multiple control domains are used in control services, the transient state problem can occur causing the service flow interruption when border switches are updated asynchronously. We analyze the uniqueness of this problem for SDN, and propose a light-weight protocol for safe reconfiguration of the border switches in order to improve the availability of the services running in SDN. Our solution is designed as a generic supervision layer added in the control plane to support different types of services. To demonstrate the benefits, we implement a prototype of Informationcentric networks (ICN) with the protocol, and conduct experiments using PlanetLab. The results show the ICN service can continuously serve high volume requests for contents despite the congestions built by the heavy background traffic. The performance gains in terms of the mean and standard deviation of the content retrieve delay are 40.5% and 21.56%.

The past few years have witnessed revolutionary advances in network technology. Along with new techniques such as SDN come lots of new network security challenges. Conventional network security mechanisms are incompetent to overcome these challenges, since they are built on a static network configuration that facilitates attackers in finding the weaknesses of a network. In this article, we conceive a novel conceptual network security mechanism, the evolving defense mechanism (EDM), to resolve current and future security problems. EDM is based on a bio-inspired idea of network configuration variations. According to the security requirements of the system, the user, and the network security state, EDM selects an efficient network configuration variation strategy to prevent corresponding security threats. Combined with SDN implementation, EDM resolves security problems from a new angle and is capable of evolving with new network security technology. We sketch a way to implement EDM and present its reference framework, which serves as an ecosystem and coexisting environment for various kinds of network configuration variations. The proposed mechanism avoids the deficiency of conventional mechanisms and has potential to cope with emerging security threats.