Dynamic circuit provisioning in all-optical WDM networks using lightpath switching

In this paper we investigate the problem of provisioning holding-time-aware (HTA) dynamic circuits in all-optical wavelength division multiplexed (WDM) networks. We employ a technique called lightpath switching (LPS) wherein the data transmission may begin on one lightpath and switch to a different lightpath at a later time. Lightpath switches are transparent to the user and are managed by the network. Allowing LPS creates a number of segments that can use independent lightpaths. We first compare the performance of traditional routing and wavelength (RWA) assignment to routing and wavelength assignment with LPS. We show that LPS can significantly reduce blocking compared to traditional RWA. We then address the problem of routing dynamic anycast HTA dynamic circuits. We propose two heuristics to solve the anycast RWA problem: anycast with continuous segment (ACS) and anycast with lightpath switching (ALPS). In ALPS we exercise LPS, and provision a connection request by searching for the best candidate destination node is such a way that the network resources are utilized efficiently. In ACS we do not allow a connection request to switch lightpaths. The lightpaths to each candidate destination node of a request are computed using traditional RWA algorithms. We first compare the performance of ACS to ALPS and observe that ALPS achieves better blocking than ACS. Furthermore, we also compare the performance of these two anycast RWA algorithms to the traditional unicast RWA algorithm. We show that the anycast RWA algorithms presented here significantly outperform the traditional unicast RWA algorithms.     

An efficient dynamic distributed optical link establish method in intelligent all-optical networks

In this article, an efficient, fast, and dynamic distributed optical link setup method is proposed. Two kinds of novel optical fast link release mechanisms (Ahead and Timeout Release) are presented for an optical-link establishment. They can dramatically reduce the blocking probability. For dynamic routing detection, a new kind of dynamic weighted Dijkstra algorithm (DW-DA) along with dynamic optical link load balancing is described. A variable mutation and crossover rates of a genetic algorithm (VMCR-GA) is used for fast wavelength assignment with two-novel-wavelength assignment rules in a wavelength relationship graph, which can reduce the necessary wavelengths and link establishment time. Through simulation giving the blocking probability and the time for link establishment on several well-known networks, the effectiveness of this method has been verified. The blocking probability of the network can be reduced significantly below that of normal routing and wavelength assignment (RWA). Furthermore, the calculating time for reaching the minimum blocking probability can be reduced dramatically.

Enhancing network resources utilization and resiliency in multi-domain bandwidth on demand service provisioning using SDN

Telecommunication Systems - This paper presents a solution to increase bandwidth utilization and to reduce the time necessary to recover from network failures in multi-domain bandwidth on demand...     

Optical dynamic intelligent network services (ODIN): an experimental control-plane architecture for high-performance distributed environments based on dynamic lightpath provisioning

Currently, many large-scale, resource-intensive applications and services are being developed that can be supported only with high-performance, highly distributed, heterogeneous infrastructures, including grids. This type of infrastructure is particularly effective for supporting applications and services that must quickly adjust to continuously changing conditions. Such processes require the flexibility of highly adaptive, dynamic, and deterministic resource provisioning. One such architecture is described here. To enhance the performance and flexibility of distributed environments, an experimental architecture for optical dynamic intelligent network (ODIN) services has been designed to enable core optical network capabilities to extend to edge processes, including applications. This architecture allows those processes to directly address arid control core network resources, for example, individual lightpaths on demand. This approach supports flexible and deterministic communications by integrating signaled requirements with adjustable network resources. An experimental prototype of ODIN has been designed, developed, and implemented on several optical network testbeds.     

QoS provisioning dynamic connection-admission control for multimedia wireless networks using a Hopfield neural network

This paper presents a quality-of-service (QoS) provisioning dynamic connection-admission control (CAC) algorithm for multimedia wireless networks. A multimedia connection consists of several substreams (i.e., service classes), each of which presets a range of feasible QoS levels (e.g., data rates). The proposed algorithm is mainly devoted to finding the best possible QoS levels for all the connections (i.e., QoS vector) that maximize resource utilization by fairly distributing wireless resources among the connections while maximizing the statistical multiplexing gain (i.e., minimizing the blocking and dropping probabilities). In the case of congestion (overload), the algorithm uniformly degrades the QoS levels of the existing connections (but only slightly) in order to spare some resources for serving new or handoff connections, thereby naturally minimizing the blocking and dropping probabilities (it amounts to maximizing the statistical multiplexing gain). The algorithm employs a Hopfield neural network (HNN) for finding a QoS vector. The problem itself is formulated as a multi-objective optimization problem. Hardware-based HNN exhibits high (computational) speed that permits real time running of the CAC algorithm. Simulation results show that the algorithm can maximize resource utilization and maintain fairness in resource sharing, while maximizing the statistical multiplexing gain in providing acceptable service grades. Furthermore, the results are relatively insensitive to handoff rates.     

Differential service in high-speed interconnection systems: analgorithm for prioritized access

The requirement to connect high-performance components of supercomputer systems has caused an increasing demand for connection-oriented, high-speed communication in a peer-to-peer environment. The importance of this type of communication is underscored by the advent of the high-performance parallel interface (HIPPI) standard, designed to support the commercial development of interconnection systems for this environment. For such interconnection systems, we present a connection management algorithm that supports priorities to provide preferential access for important classes of traffic, and that assures equitable access for all connections within the same priority class. At the same time, the algorithm utilizes the connection resources efficiently and assures low overhead at the nodes. We demonstrate the algorithm's applicability by outlining a centralized as well as a distributed implementation in an HIPPI-based interconnection system. Furthermore, we introduce an analytic priority model that can be used to evaluate an interconnection system's performance under the algorithm. Using this model, we analyze the efficacy of the nonpreemptive priority discipline and show the load/throughput behavior of a typical system     

A flexible and distributed architecture for adaptive end-to-end QoS provisioning in next-generation networks

A novel distributed end-to-end quality-of-service (QoS) provisioning architecture based on the concept of decoupling the end-to-end QoS provisioning from the service provisioning at routers in the differentiated service (DiffServ) network is proposed. The main objective of this architecture is to enhance the QoS granularity and flexibility offered in the DiffServ network model and improve both the network resource utilization and user benefits. The proposed architecture consists of a new endpoint admission control referred to as explicit endpoint admission control at the user side, the service vector which allows a data flow to choose different services at different routers along its data path, and a packet marking architecture and algorithm at the router side. The achievable performance of the proposed approach is studied, and the corresponding results demonstrate that the proposed mechanism can have better service differentiation capability and lower request dropping probability than the integrated service over DiffServ schemes. Furthermore, it is shown that it preserves a friendly networking environment for conventional transmission control protocol flows and maintains the simplicity feature of the DiffServ network model.     

CHEETAH virtual label switching router for dynamic provisioning in IP optical networks

Enabling new IP-based services such as triple and quad-play, as well as eScience applications at predetermined quality of service (QoS) measures, require the provisioning of guaranteed bandwidth pipes at varying granularities (e.g. from few Mbps to several Gbps and above). Dynamic provisioning of bandwidth pipes, whereby a connection is dynamically setup and released upon signalling, is a cost-effective method of enabling such services. Dynamic provisioning is a new paradigm in network control and management (NC&M) that requires the introduction of control plane (i.e. routing and signaling) capabilities within network elements such as routers, layer 2 switches and layer 1 cross-connects.In this paper we share our experience in the design and deployment of a Generalized Multiple Protocol Label Switching (GMPLS) control plane for layer 2 switches in the experimental Circuit-Switched High-Speed End-to-End Transport Architecture (CHEETAH). We call this software engine CHEETAH Virtual Label Switching Router (CVLSR). CVLSR allows non-GMPLS devices (e.g. Ethernet switches, routers and other cross-connects) to participate in the dynamic provisioning of end-to-end bandwidth-guaranteed connections. It extends the dynamic provisioning of connections to the end-users across different administrative domains. We have successfully deployed the CVLSR in CHEETAH optical network across HOPI/DRAGON network. The interoperability of the CVLSR with commercial GMPLS SONET-based cross-connect switches has been demonstrated.     

Real Time ML-Based QoE Adaptive Approach in SDN Context for HTTP Video Services

Wireless Personal Communications - Due to the high dynamism of network conditions, operators and service providers are facing the challenge of providing satisfactory user experience during a...     

Secure access of resources in software‐defined networks using dynamic access control list

Software‐defined networking (SDN) creates a platform to dynamically configure the networks for on‐demand services. SDN can easily control the data plane and the control plane by implementing the decoupling concept. SDN controller will regulate the traffic flow and creates the new flow label based on the packet dump received from the OpenFlow virtual switches. SDN governs both data information and control information toward the destination based on flow label, but it does not contain security measure to restrict the malicious traffic. The malicious denial‐of‐service (DoS) attack traffic is generated inside the SDN environment; it leads to the service unavailability. This paper is mainly focused on the detection of DoS attacks and also mitigates the malicious traffic by dynamically configuring the firewall. The SDN with dynamic access control list properties is emulated by mininet, and the experimental results exemplify the service unavailable gap between acceptance and rejection ratio of the packets.     

Multiple preemptive EDCA for emergency medium access control in distributed WLANs

The increasingly use of wireless local area networks (WLANs) in public safety and emergency network services demands for a strict quality of service (QoS) guarantee especially a large number of users report an emergency for immediate channel access. Unfortunately, the traditional IEEE 802.11e-based enhanced distributed channel access (EDCA) does not support a strict QoS guarantee for life saving emergency traffic under high loads. Previous studies have attempted to enhance the performance of EDCA called the Channel Preemtive EDCA (CP-EDCA) which is a promising idea to support emergency traffic in WLANs. However, CP-EDCA supports a single emergency traffic only (i.e. no emergency service differentiation) with high delays for increased traffic loads. To overcome this problem, we propose a class of EDCA protocol called Multiple Preemption EDCA (MP-EDCA) as a candidate to support multiple emergency traffics under high loads. Each MP-EDCA node can support up to four emergency traffics (life, health, property and environment) with different priorities in addition to support background (non-emergency) traffic. The proposed protocol privileged the high priority life-saving emergency traffic to preempt the services of low priority ones without much starvation in the network to maintain a strict QoS guarantee. The paper evaluates the performance of MP-EDCA through an extensive analysis of simulation outcome. The results obtained show that MP-EDCA outperforms CP-EDCA in achieving lower medium access control and emergency node delays.     

Adaptive control for random access traffic in mobile radio systems

An adaptive random access control method is developed for the idle-signal-casting multiple-access (ICMA) or other random-access protocols. Its purpose is to prevent channel breakdown by controlling permission probabilities of user terminal's transmission according to the load of a random-access channel. In ICMA, a base station broadcasts an `idle' or `busy' signal to prevent collisions of random access signals from terminals. Two kinds of control parameters related to permission probabilities are used. Probability q is referred to by all user terminals attempting transmission, and probability p is referred to if a user terminal must wait for the end of another's transmission. The values of these parameters are determined according to the channel occupancy factor measured at a base station, and the base station broadcasts them to user terminals with `idle' or `busy' signals. This method can prevent channel breakdown and greatly improve channel performance under heavy-traffic conditions. Results of evaluating the method by computer simulation are discussed     

分布式存储系统中数据修复的自适应流控机制

要大规模分布式存储系统中存在大量的数据迁移和数据修复任务,一方面要尽量缩短数据修复时间以降低数据丢失风险,另一方面需要避免这类任务对正常业务的服务质量造成冲击。针对该需求,文中提出一种自适应的数据修复流控机制。通过周期性的相对负载变化检测来动态调整修复流量大小,并根据数据危险级别和全局负载信息决定修复任务优先级。实验表明,该方法不仅能够提高大规模分布式存储系统的数据修复效率,避免对正常业务性能造成明显冲击,还具有自适应的优点。     

Technique for authentication, access control and resource management in open distributed systems

A consistent approach to authentication and access control is proposed. In this new approach, resource management is included. By combining the properties of public key encryption with cascading proxies a single mechanism is devised to provide these three aspects of protection.<>     

Adaptive minimum bit feedback for sum-rate analysis in multi-user distributed antenna systems

The paper mainly studies the sum-rate performance of limited feedback (LFB) block-diagonalization (BD) in multi-user distributed antenna system (DAS). As the channel state information (CSI) fed back to base station (BS) is limited, multi-user interference (MUI) is caused inevitably because of the quantization error. Considering the influence of the MUI to the capacity of DAS, we propose a parameter of effective sum-rate ratio (ESRR) to denote the capacity offset under the condition of the BS can get perfect CSI and limited CSI first, then we confirm that the approximated ESRR is very close to actual ESRR got through simulations. After that, based on the approximated ESRR, an adaptive minimum bit feedback scheme which can effectively reduce the overhead of feedback channel and the complexity of the system is proposed. Simulation results show the effectiveness of the proposed scheme.     

车联网中基于分布式博弈的移动网关选取算法

提出一种基于VANET-CELLULAR混合架构的车联网(VANET)。在这种架构下,车辆可以根据一些原则动态成簇,在这些簇中,通过车辆间分布式博弈快速选取最少数量的车辆作为移动网关,将本地VANET接入蜂窝网络,并随着簇的网络拓扑变化动态更新网关,以最大化车辆数据传输的性能。考虑到车辆节点的自私特点,分布式博弈可以有效地提高移动网关节点的积极性,使得算法的可行性增强。仿真结果表明该算法能高效选取车联网移动网关。     

Three-step impedance criterion for small-signal stability analysis in two-stage DC distributed power systems

Small-signal stability analysis methods based on an impedance criterion originate from the minor loop gain method and are gradually utilized in two-stage DC distributed power systems. In this paper, we conclude that the impedance criterion directly dependent on output impedance Z/sub o/(s) of the source subsystem and input impedance Z/sub i/(s) of the load subsystem is possible but gives an incorrect stability analysis for systems with a regulated source subsystem. Through introducing a mapped pure impedance of the load subsystems and the preliminary system, we develop a general three-step impedance criterion, with which a correct small-signal stability analysis can be guaranteed, regardless of the type of source subsystem. Furthermore, we introduce the application of the three-step impedance criterion in two small-signal stability analysis cases and utilize it in an example system to predict the stability shift process arising from the variation on the load resistance and input voltage value.