Restoration message transfer mechanism and restorationcharacteristics of double-search self-healing ATM network

The self-healing network is particularly interesting with regard to ATM networks, because the restoration time can be shortened by using the advantages of the ATM network. This paper studies a self-healing ATM network based on virtual path (VP) protection switching. First, a novel self-healing algorithm-the double-search self-healing algorithm-is proposed. It is shown that this algorithm can restore failed bidirectional VPs faster and find alternate VPs more effectively than existing self-healing algorithms. Second, it is shown that the restoration information for self-healing control (SHC) messages must be transferred by specific cells carrying the control and OAM information (Ic&o). Message parameters and a cell format are proposed. Third, evaluation of the restoration characteristics using the proposed self-healing algorithm by computer simulation indicates that good performance against a transmission link failure is obtained even in a large-scale network model with 110 nodes. The results also indicate that the VP group (VPG) method can improve the restoration time without reducing the restoration ratio     

Multiple-availability-level ATM network architecture

Because of their high flexibility, ATM networks have the potential to achieve two objectives: switch cost reduction and multi-level network availability. For that purpose, this article proposes to use virtual circuit (VC) route self-healing schemes to achieve a multiple-availability-level ATM network. Flexible multi-QoS logical ATM network (Full-Net), a new concept for ATM networks, is now being studied at NTT Laboratories. Full-Net is a very flexible network design strategy for survivable networks that is based on a self-healing VC network. Defining several logical configurations of the VC network allows us to support multiple levels of network availability, simplifies the adaptation to future and unknown service requirements, and significantly reduces overall ATM network cost. Offering different levels of availability not only saves the network's resources, but also allows the network operator to provide its customers with services at the most appropriate cost. We introduce the advantages of VC route restoration for ATM networks, and compare virtual path (VP) level and physical level restoration strategies. We explain Full-Net's concept, propose a VC route self-healing scheme, and show the impact of the logical network configurations on network survivability and resource management     

ATM VPX生存网络的综合控制策略

ＡＴＭＶＰ交叉连接（ＶＰＸ）网络自愈得以了深入的研究，网络自愈也是一个控制问题，然而在以往的文献中，常规控制和自愈控制是分开研究的，本文首次提出了ＡＴＭＶＰＸ生存网络的综合控制策略，把两者有机地结合在起来，作为一整体来设计，以降低控制复杂度，并通过计算机模拟验证了该策略的可操作性和正确性，该控制策略能够运行在常规条件下和发生故障环境中，使得网络规划和设计达到成本有效性要求。     

ATM网络中语音编码和传输的新方案

本文针对未来新的ＡＴＭ通信方式,提出了一种新的语音可变速率编码和可变时延传输系统方案,为了将信号源和人耳听觉的特征,与ＡＴＭ网络的统计复用性相结合,实现语音的码率在缩和低时延传输,该方案将ＡＴＭ网络环境和语音编码系统中最优信号分析区间的选取、编码系统参数的确定相结合。文中基于一种新的分布熵进行信号特征判断,对输入信号构成不同的处理系统,具体编码由小波变换分带、多带二进树ＶＱ构成,输出码率可调,改变     

无线传感器网络中自治愈的群组密钥管理方案

 群组密钥管理的自治愈机制是保证无线传感器网络在不可靠信道上进行安全群组通信的重要 手段.基于采用双方向密钥链的群组密钥分发与撤销方法,提出了一个无线传感器网络中具有撤销能力的自治愈群组密钥管理方案.该方案实现了群组密钥的自治愈功能和节点撤销能力, 能够满足在较高丢包率的无线通信环境下传感器网络群组密钥管理的安全需求,确保了群组密钥保密性、前向保密性和后向保密性等安全属性.性能分析表明,该方案具有较小的计算和通信开销,能够适用于无线传感器网络.     

Restoration strategies and spare capacity requirements inself-healing ATM networks

This paper studies the capacity and flow assignment problem arising in the design of self-healing asynchronous transfer mode (ATM) networks using the virtual path concept. The problem is formulated here as a linear programming problem which is solved using standard methods. The objective is to minimize the spare capacity cost for the given restoration requirement. The spare cost depends on the restoration strategies used in the network. We compare several restoration strategies quantitatively in terms of spare cost, notably: global versus failure-oriented reconfiguration, path versus link restoration, and state-dependent versus state-independent restoration. The advantages and disadvantages of various restoration strategies are also highlighted. Such comparisons provide useful guidance for real network design. Further, a new heuristic algorithm based on the minimum cost route concept is developed for the design of large self-healing ATM networks using path restoration. Numerical results illustrate that the heuristic algorithm is efficient and gives near-optimal solutions for the spare capacity allocation and flow assignment for tested examples     

A self-healing ATM network based on multilink principles

Self-healing is the ability of a network to reconfigure itself around failures such that calls in progress are not dropped and suffer of no or almost no degradation in quality of service. Providing self-healing capabilities in all parts of the future ATM network in a cost effective way is therefore a key challenge. A new self-healing method based on the multilink concept is presented for dedicated parts of the ATM network, such as, for instance, feeder networks. In the multilink concept that is proposed, the cells of an ATM connection carried by a multilink are distributed over several physical links. If a physical link supporting the multilink fails, the cells will be distributed among the remaining physical links thus providing a self-healing capacity. In this way the quality of service can be maintained at the expense of a higher load on the remaining physical links. The speed of restoration only relies on the detection and signaling of the failure since spare capacity is available on the very multilink. The sharing of spare capacity in addition to the statistical multiplexing gain provides a cost effective self-healing method and leads to a simplified network resource management. The proposed multilink concept is based on an extension of the multipath self-routing concept, which is currently applied by Alcatel in its ATM switching fabric     

Reducing signaling traffic in wireless ATM networks through handoff scheme improvement

We propose a new handoff call management scheme which reduces signaling traffic in wireless ATM networks and improves the efficiency of the virtual channel. Chaining followed by a make‐break algorithm is a suitable handoff scheme for various situations. In the chaining part of the scheme, a chain routing algorithm is studied and compared with the hop‐limiting scheme. When the algorithm is implemented in our scheme, it improves the performance of the existing scheme in call drop rates so as to reduce the signaling traffic in wireless ATM networks. Copyright © 2002 John Wiley & Sons, Ltd.     

Architectures for ATM network survivability

This article surveys the restoration architectures for asynchronous transfer mode (ATM) network survivability that have been actively studied in this decade. Network reliability is critical for recent and future networks that will advance the information era. Moreover, it is one of the biggest factors in designing and managing networks. Since the early telecom network era, many restoration systems have been developed for plesiochronous digital hierarchy (PDH), synchronous digital hierarchy (SDH), synchronous optical network (SONET), leased lines and so on; and they were surveyed in many papers and books. This article focuses on new restoration techniques for ATM networks. First, the requirement studies are introduced. This includes the scant results published on the influence of failure and the state of failure analysis. Next, restoration schemes are categorized and briefly introduced. Examples include centralized control, automatic protection switch (APS), self-healing ring (SHR), self-healing network (SHN) and failure resistant virtual path (FRVP). In order to achieve adequate restoration probability with minimum cost, a network design scheme is necessary; thus, network design issues are introduced. Finally, this article focuses on the issues, future work, and problems that remain to be solved.     

Self-healing ATM networks based on virtual path concept

This paper proposes self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN. First, the characteristics of the virtual paths (VP) and their influence on failure restoration are discussed. A high-speed restoration technique which exploits the benefits of the VP is then proposed and described. The technique simplifies the message transmission processes and reduces the number of generated messages by using preassigned backup virtual paths. Next, the scheme used to design the backup VP routes and spare resource distribution for each link is proposed in order to create a network that applies the proposed restoration scheme. Next, self-reconstruction techniques of backup virtual paths are proposed for the realization of a reversionless restoration cycle. Finally, the feasibility of the distributed control operation is discussed     

Integrated VP-Based Control Strategies for ATM Survivable Networks

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An efficient feedback consolidation algorithm forpoint-to-multipoint ABR service in ATM network

In this letter, we propose an efficient feedback consolidation algorithm for a point-to-multipoint available bit rate (ABR) service in asynchronous transfer mode (ATM) networks. The proposed scheme can achieve fast transient response to the congestion status on a branch as well as effectively eliminate the consolidation noise     

A Novelistic GSA and CSA Based Optimization for Energy-Efficient Routing Using Multiple Sinks in HWSNs Under Critical Scenarios

Asynchronous transfer mode (ATM) tends to be the most mature infrastructure to serve the imminent media broadband networks and is intended to eliminate network latency and improve traffic output versatility. In Weighted Round Robin (WRR) scheme, the main cause of concern is the delay that is being caused by high volumes of workloads at the wireless source nodes. In this paper, proposed an efficient intelligent time slice based round Robin scheduling algorithm for ATM with the use of integrated speed bit protocol (ISBP). The intelligent time slice offers priority, the blast of the CPU, and the time meaning transfer. The speed bit manager is maintained by the ISBP that contains prioritized objects. Then the intelligent time slice is done to generate the quantum time value. The purpose of this paper to enhance network performance in ATM networks by improving the throughput and average end-to-end delay. The new proposed scheme also offers a significant reduction in the average end-to-end delay when compared to the existing WRR scheme.

     

One-way hash chain-based self-healing group key distribution scheme with collusion resistance capability in wireless sensor networks

In order to resolve the collusion resistance problem in the one-way hash chain-based self-healing group key distribution schemes and improve the performance of previous self-healing group key distribution schemes, we propose a self-healing group key distribution scheme based on the revocation polynomial and a special one-way hash key chain for wireless sensor networks (WSNs) in this paper. In our proposed scheme, by binding the time at which the user joins the group with the capability of recovering previous group session keys, a new method is addressed to provide the capability of resisting the collusion attack between revoked users and new joined users, and a special one-way hash chain utilization method and some new methods to construct the personal secret, the revocation polynomial and the key updating broadcast packet are presented. Compared with existing schemes under same conditions, our proposed scheme not only supports more revoked users and sessions, but also provides a stronger security. Moreover, our proposed scheme reduces the communication overhead, and is especially suited for a large scale WSN in bad environments where a strong collusion attack resistance capability is required and many users will be revoked.     

A new cell loss recovery method using forward error correction in ATM networks

A new method using an FEC technique is proposed to enhance the ability of consecutive cell loss compensation due to buffer overflow in ATM networks. This article summarizes different applications of cell loss recovery, and presents the design of a new coding scheme and the coding/decoding algorithm. © 1998 John Wiley & Sons, Ltd.     

基于柔性QoS的资源动态分配策略研究

本文在对QoS的柔性,描述和评价方法进行研究的基础上,针对频率资源有限的无线ATM网,提出了利用QoS的柔性在业务过程中对频率资源进行动态分配的方案和算法,并进行了实验仿真,结果表明利用QoS的柔性动态分配频率资源可以提高资源的利用率。     

一种无线ATM网络的MAC协议

主要研究了无线ATM网络对MAC的需求，并介绍了适用于无线ATM的一种新的MAC方案。该协议支持不同类型信息传输，比如恒定比特率（CBR），可变比特率（VBR），可用比特率（ABR），未指定比特率（UBR）。另外此协议还提供了对宽带ATM主干网的无缝连接。同时也支持与ATM相关的QoS级别。对于该协议关注的各种情况的主要原理进行了讨论。     

Dynamic scope location tracking algorithm for mobile PNNI scheme inwireless ATM networks

The authors propose an enhanced location tracking algorithm for the mobile PNNI scheme in wireless ATM networks. The main contribution is the use of the dynamic reachability scope depending on the mobile endpoint's movement rate and terminating call rate without any modifications to the mobile PNNI scheme. As a result, the proposed algorithm can reduce the location management cost compared with the original mobile PNNI scheme having a fixed scope value     

Optimal capacity and flow assignment for self-healing ATM networksbased on line and end-to-end restoration

This paper addresses an optimal link capacity design problem for self-healing asynchronous transfer mode (ATM) networks based on two different restoration schemes: line restoration and end-to-end restoration. Given a projected traffic demand, capacity and flow assignment is jointly optimized to find an optimal capacity placement. The problem can be formulated as a large-scale linear programming. The basis matrix can be readily factorized into an LU form by taking advantage of its special structure, which results in a substantial reduction on the computation time of the revised simplex method. A row generation and deletion mechanism is developed to cope with the explosive number of constraints for the end-to-end restoration-based networks. In self-healing networks, end-to-end restoration schemes have been considered more advantageous than line restoration schemes because of a possible reduction of the redundant capacity to construct a fully restorable network. A comparative analysis is presented to clarify the benefit of end-to-end restoration schemes quantitatively in terms of the minimum resource installation cost. Several networks with diverse topological characteristics as well as multiple projected traffic demand patterns are employed in the experiments to see the effect of various network parameters. The results indicate that the network topology has a significant impact on the required resource installation cost for each restoration scheme. Contrary to a wide belief in the economic advantage of the end-to-end restoration scheme, this study reveals that the attainable gain could be marginal for a well-connected and/or unbalanced network     

Control protocol and its performance analysis for distributed ATMvirtual path self-healing network

A restorable network comprised of a mesh of ATM virtual paths (AVPs) is expected to be superior to distributed SONET digital cross-connect self-healing networks in terms of restoration time. The paper presents a reliable protocol and evaluation of its performance for control information transfer in distributed AVP self-healing networks. Two error-recovery technologies for the data-link level (selective retransmission and go-back-N) in AVP networks are reviewed, and a model for evaluating the delay of the go-back-N method that has been used in existing terrestrial systems is derived analytically. The proposed analytic model is combined with a self-healing simulator for AVP mesh networks to evaluate the restoration time characteristics. Case study results for the worst-case scenario show that the total restoration time, including link-by-link error control for self-healing control messages, is expected to be less than 2 s, which is the time objective for complete restoration for a metropolitan LATA network. The results also show that the estimated average delay penalty for adding the link-by-link error recovery process is 7.5 ms for complete service restoration