Providing QoS guarantees to unicast and multicast flows in multistage packet switches

Multistage packet switches that feature a limited amount of buffers in the switching fabric and distribute most of their buffering capacity over the port cards have recently gained popularity due to their scalability properties and flexibility in supporting quality-of-service (QoS) guarantees. In such switches, the replication of multicast packets typically occurs in-the fabric. This approach minimizes the amount of resources needed to sustain the internal expansion in traffic volume due to multicasting, but also exposes multicast flows to head-of-line (HOL) blocking in the ingress port cards. The distributed scheduler that arbitrates the transfer of packets through the switch and the flow-control scheme that restricts access to the fabric buffers have the most critical role in safeguarding the QoS guarantees of multicast flows against HOL blocking. We add minimal overhead to a well-known QoS framework for multistage packet switches to define the generalized distributed multilayered scheduler (G-DMS), which achieves full support of QoS guarantees for both unicast and multicast flows. The main novelty of the G-DMS is in the mechanism that regulates access to the fabric buffers, which combines selective backpressure with the capability of dropping copies of multicast packets that violate the negotiated profiles of the corresponding flows.     

MPLS security: an approach for unicast and multicast environments

Multi-Protocol Label Switching (MPLS) network architecture does not protect the confidentiality of data transmitted. This paper proposes a mechanism to enhance the security in MPLS networks by using multi-path routing combined with a modified (k, n) threshold secret sharing scheme. An Internet Protocol (IP) packet entering MPLS ingress router can be partitioned into n shadow (share) packets, which are then assigned to maximally node disjoint paths across the MPLS network. The egress router at the end will be able to reconstruct the original IP packet if it receives any k share packets. The attacker must therefore tap at least k paths to be able to reconstruct the original IP packet that is being transmitted, while receiving k???1 or less of share packets makes it hard or even impossible to reconstruct the original IP packet. In this paper, we consider the multicast case in addition to the unicast. To our best knowledge, no work has been published for MPLS multicast security. We have implemented our model and measured its time complexity on variable packets size.     

Multicast delivery based on unicast and subnet multicast

In spite of the numerous works previously made, IP multicasting has not been widely deployed in the public Internet. We present a realistic alternative scheme for IP multicasting, which is based on the unicast transport from a remote sender to a local subnet and the multicast forwarding to receivers within the subnet     

Minimum-cost QoS multicast and unicast routing in communication networks

In this paper, we study the minimum-cost quality-of-service multicast and unicast routing problems in communication networks. For the multicast problem, we present an efficient approximation algorithm to find a balance between a minimum-cost multicast tree and a minimum-delay multicast tree, with a provably good performance under the condition that link delay and link cost are identical. For the unicast problem, we present an efficient primal-dual heuristic algorithm to find a path which balances path cost and path delay, together with an error bound. The lack of a provably good performance for the second algorithm is complemented by computational results on randomly generated networks. Our algorithm finds optimal solutions in more than 80% of the cases and finds close to optimal solutions in all other cases, while using much less time.     

Performance evaluation of legacy QCN for multicast and multiple unicast traffic transmission

A multicast congestion control scheme is an interesting feature to control group communication applications such as teleconferencing tools and information dissemination services. This paper addresses a comparison between multiple unicast and multicast traffic congestion control for Carrier Ethernet. In this work, we proposed to study the quantized congestion notification (QCN), which is a layer 2 congestion control scheme, in the case of multicast traffic and multiple unicast traffic. Indeed, the QCN has recently been standardized as the IEEE 802.1Qau Ethernet Congestion Notification standard. This scheme is evaluated through simulation experiments, which are implemented by the OMNeT++ framework. This paper evaluates the reaction point start time congestion detection, feedback rate, loss rate, stability, fairness and scalability performance of the QCN for multicast traffic transmission and multiple unicast traffic transmission. This paper also draws a parallel between QCN for multicast traffic transmission and that for multiple unicast traffic transmission. Despite the benefit of integrating the multicast traffic, results show that performance could degrade when the network scales up. The evaluation results also show that it is probable that the feedback implosion problem caused by the bottlenecks could be solved if we choose to set the queue parameter Qeq threshold value at a high value, 75% of the queue capacity for instance. Copyright © 2016 John Wiley & Sons, Ltd.     

A cost-benefit flow control for reliable multicast and unicast in overlay networks

When many parties share network resources on an overlay network, mechanisms must exist to allocate the resources and protect the network from overload. Compared to large physical networks such as the Internet, in overlay networks the dimensions of the task are smaller, so new and possibly more effective techniques can be used. In this work we take a fresh look at the problem of flow control in multisender multigroup reliable multicast and unicast and explore a cost-benefit approach that works in conjunction with Internet standard protocols such as TCP. In contrast to existing window-based flow control schemes, we avoid end-to-end per sender or per group feedback by looking only at the state of the virtual links between participating nodes. This produces control traffic proportional only to the number of overlay network links and independent of the number of groups, senders, or receivers. We show the effectiveness of the resulting protocol through simulations and validate the simulations with live Internet experiments. We demonstrate near-optimal utilization of network resources, fair sharing of individual congested links, and quick adaptation to network changes.     

组播/单播OFDMA系统中资源分配算法研究

本文研究了组播/单播OFDMA系统中的无线资源分配,为了在满足组播速率需求的条件下最大化单播用户的总速率的优化目标,提出两种资源分配算法.分别采用代价函数和适度度量作为依据为组播用户选择子载波,剩余资源按照最大吞吐量准则分配给单播用户.仿真表明,两种算法均能够满足组播速率需求,且获得的单播用户的总速率接近理论最大值.     

Write policies for multicast ATM switches

A unicast and multicast-pushout write policy for shared-memory ATM switches is proposed. The scheme allocates buffers based on the service rates of unicast and multicast cells to ensure that maximum throughput can be maintained     

Multiservice unicast/multicast communications over IEEE 802.11e networks

Wireless communications are nowadays one of the most active research and development areas in telecommunications. The widespread use of wireless networks and the development of high-rate infrastructure are in turn enabling the introduction and deployment of many new end-user applications. During the past few years, the IEEE 802.11e (EDCA) standard has been working on defining the required QoS mechanisms to be incorporated into the IEEE 802.11 protocol architecture. However, recent studies have shown that EDCA performs poorly when the medium is highly loaded due to the high collision rate. Numerous proposals have been reported in the literature aiming to overcome this main drawback. However, EDCA and the proposed mechanisms continue to have a serious problem with a specific type of application: the multicast traffic. In EDCA (as in DCF) the multicast service is defined as an unreliable service, i.e., it does not include the use of ACK frames. Furthermore, different to the unicast service, the multicast service makes use of a single rate out of the various rates included in the Basic Service Set (BSS) defined by the IEEE 802.11 standard. This situation has led many researchers to design techniques aiming to improve the multicast transmission. In this paper, we analyze the inter-operability of two prominent multicast mechanisms recently reported by the authors and the channel access method defined by the IEEE 802.11e EDCA standard. We further consider the use of B-EDCA: an enhanced version of EDCA recently introduced by the authors. We carried a comparative performance evaluation of the aforementioned mechanisms when supporting unicast and multicast traffic. Our simulation results show the effectiveness of the enhanced protocol architectures when jointly supporting unicast and multicast traffic.     

对于IP地址攻击有效的混合蜜罐入侵检测系统

提出在入侵检测系统中融合蜜罐技术并应用在分布式的网络环境中。主要目的就是通过单播IP地址攻击和组播的IP地址攻击对比单独入侵检测系统与融合了蜜罐技术的入侵检测系统检测攻击的有效性。混合蜜罐网络由Snort和Honeyd组成,Snort的作用是入侵检测而Honeyd组成蜜罐系统。Honeyd安装在Linux系统中,这个系统的传感器探测Snort和Honeyd是否传送数据到主数据库。使用NESSUS对实验数据进行分析。提供给管理员一种更有效的网络管理方式。     

Min-max load balancing scheme for mixed multicast and unicast services in LTE networks

To avoid the traffic congestion in long term evolution (LTE) networks,a min-max load balancing (LB) scheme is proposed to minimize the demanded radio resources of the maximum loaded cell.For the mixed ...     

A scalable approach to the partition of QoS requirements in unicast and multicast

Supporting quality of service (QoS) in large-scale broadband networks poses major challenges, due to the intrinsic complexity of the corresponding resource allocation problems. An important problem in this context is how to partition QoS requirements along a selected topology (path for unicast and tree for multicast). As networks grow in size, the scalability of the solution becomes increasingly important. This calls for efficient algorithms, whose computational complexity is less dependent on the network size. In addition, recently proposed precomputation-based methods can be employed to facilitate scalability by significantly reducing the time needed for handling incoming requests. We present a novel solution technique to the QoS partition problem(s), based on a "divide-and-conquer" scheme. As opposed to previous solutions, our technique considerably reduces the computational complexity in terms of dependence on network size; moreover, it enables the development of precomputation schemes. Hence, our technique provides a scalable approach to the QoS partition problem, for both unicast and multicast. In addition, our algorithms readily generalize to support QoS routing in typical settings of large-scale networks.     

Bounds on the throughput gain of network coding in unicast and multicast wireless networks

Gupta and Kumar established that the per node throughput of ad hoc networks with multi-pair unicast traffic scales with an increasing number of nodes n as lambda(n) = ominus(1/radic(n log n)), thus indicating that performance does not scale well. However, Gupta and Kumar did not consider network coding and wireless broadcasting, which recent works suggest have the potential to significantly improve throughput. Here, we establish bounds on the improvement provided by such techniques. For random networks of any dimension under either the protocol or physical model that were introduced by Gupta and Kumar, we show that network coding and broadcasting lead to at most a constant factor improvement in per node throughput. For the protocol model, we provide bounds on this factor. We also establish bounds on the throughput benefit of network coding and broadcasting for multiple source multicast in random networks. Finally, for an arbitrary network deployment, we show that the coding benefit ratio is at most O(log n) for both the protocol and physical communication models. These results give guidance on the application space of network coding, and, more generally, indicate the difficulty in improving the scaling behavior of wireless networks without modification of the physical layer.     

A framework for routing and congestion control for multicast information flows

We propose a new multicast routing and scheduling algorithm called multipurpose multicast routing and scheduling algorithm (MMRS). The routing policy load balances among various possible routes between the source and the destinations, basing its decisions on the message queue lengths at the source node. The scheduling is such that the flow of a session depends on the congestion of the next hop links. MMRS is throughput optimal. In addition, it has several other attractive features. It is computationally simple and can be implemented in a distributed, asynchronous manner. It has several parameters which can be suitably modified to control the end-to-end delay and packet loss in a topology-specific manner. These parameters can be adjusted to offer limited priorities to some desired sessions. MMRS is expected to play a significant role in end-to-end congestion control in the multicast scenario.     

Dynamic provisioning of low-speed unicast/multicast traffic demands in mesh-based WDM optical networks

This paper addresses the problem of dynamically provisioning both low-speed unicast and multicast connection requests in mesh-based wavelength division multiplexing (WDM) optical networks. Several routing/provisioning schemes to dynamically provision both unicast and multicast connection requests are presented. In addition, a constraint-based grooming strategy is devised to utilize the overall network resources as efficiently as possible. Based on this strategy, several different sequential multicast grooming heuristics are first presented. Then, we devise a hybrid grooming approach and combine it with sequential approaches to achieve a grooming scheme that is biased toward serving multicast traffic demands in comparison with all other sequential grooming approaches. To achieve our objective, we decompose the problem into four subproblems: 1) routing problem; 2) light-tree-based logical-topology-design problem; 3) provisioning problem; and 4) traffic-grooming problem. The simulation results of the proposed schemes are compared with each other and with those of conventional nongrooming approaches. To the best of our knowledge, this is the first detailed paper to address and examine the problem of grooming dynamic multicast traffic demands.     

基于双向共享树的MPLS多播流聚合算法

可扩展性是影响多播在MPLS网络大规模使用的主要问题,为解决该问题提出了一种基于双向共享树的多播流聚合算法.它根据节点之间的关系计算多播流的可聚合度,然后将标记边缘路由器聚类生成共享树的叶子节点集,并由树管理服务器计算双向共享树的拓扑结构,最后将可聚合度大于指定阈值的多播流汇聚到树中.实验结果表明,该算法可以大幅缩小MPLS标记的占用,简化中间节点的处理过程,减少路由器的转发状态,大大提高了MPLS多播的可扩展性.     

Congestion control for fair resource allocation in networks with multicast flows

We consider the problem of congestion control in networks which support both multirate multicast sessions and unicast sessions. We present a decentralized algorithm which enables the different rate-adaptive receivers in different multicast sessions to adjust their rates to satisfy some fairness criterion. A one-bit ECN marking strategy to be used at the nodes is also proposed. The congestion-control mechanism does not require any per-flow state information for unicast flows at the nodes. At junctions nodes of each multicast tree, some state information about the rates along the branches at the node may be required. The congestion-control mechanism takes into account the diverse user requirements when different receivers within a multicast session have different utility functions, but does not require the network to have any knowledge about the receiver utility functions.     

Performance analysis of bandwidth requests under unicast, multicast and broadcast pollings in IEEE 802.16d/e

In the polling mode in IEEE 802.16d/e, one of three modes: unicast, multicast and broadcast pollings, is used to reserve bandwidth for data transmission. In the unicast polling, the BS polls each individual MS to allow to transmit a bandwidth request packet, while in the multicast and broadcast pollings, the truncated binary exponential backoff (TBEB) mechanism is adopted as a contention resolution among mobile stations (MSs) in a multicast or broadcast group. This paper investigates the delay of bandwidth requests in the unicast, multicast and broadcast pollings, by deriving the delay distribution of the unicast polling and the TBEB by means of analytical methods. We consider an error-free channel as well as an error-prone channel with i.i.d. constant packet error rate per frame. Furthermore, we find the utilization of transmission opportunity to see efficiency of the bandwidth in the TBEB. Performance evaluations are provided to show that analytical results are well-matched with simulations. By the numerical results, we can find the optimal parameters such as the initial backoff window size of the TBEB and the number of transmission opportunities (or slots) satisfying quality of service (QoS) requirement on delay and loss, and thus we can determine which scheme is better than others depending on the probability of a request arrival during one frame. Numerical examples address that the TBEB performs better than the unicast polling for light traffic loads and vice versa for heavy traffic loads. Also, it is shown that the multicast polling has better performance than the broadcast polling in the sense of shorter delay, lower loss probability and higher utilization of transmission opportunity.     

QoS单播路由算法的研究

本文在综合烽务QoS和网络性能参数的基础上,提出了一个新的路由度量标准BHD,然后提出了一种优化的QoS单播路由算法BHDR,仿真研究表该算法在满足业务连接时延要求的同时提高了网络的吞吐量,较好的改善了网络的性能。