Fair Bandwidth Allocation Using Effective Multicast Traffic Share in TDM-PONs

In this paper, the effects of optical traffic-sharing on the performance of multicast video delivery in terms of the efficiency of bandwidth allocation and the fairness of link-sharing are discussed for the downstream direction of a time-division-multiplexed passive optical network (TDM-PON). We analyze the practical issues associated with multicast packet switching and transmission control in a TDM-PON and also propose a fair bandwidth allocation mechanism, called share-based proportional bandwidth allocation (S-PBA), to effectively support multicast services. In order to provide an optical network unit with a fair amount of link bandwidth and high throughput independent of traffic type, S-PBA arbitrates the amount of unicast timeslot by using effective multicast traffic share, which is determined based on multicast traffic load distribution and traffic-sharing density. Analytic and simulation results clearly validate the effectiveness of the proposed mechanism. This work is applicable to multicast video delivery or multicast traffic transmission in general, such as voice traffic, or a combination of both in the case of video conferencing, for example.     

A novel dynamic Multiple Ring-based Local Restoration for point-to-multipoint multicast traffic in WDM mesh networks

Optical networks with DWDM (Dense Wavelength Division Multiplex) can provide multiple data channels to supply high speed, high capacity to perform bandwidth-intensive multicast transmission service. Light-tree is a popular technique applied to support point-to-multipoint multicast services. Any failure during a multicast session would cause severe service loss or disruptions, especially when the faults occur near the source node. A novel ring-based local fault recovery mechanism, Multiple Ring-based Local Restoration (MRLR), for point-to-multipoint multicast traffic based on the minimum spanning tree (MST) in WDM mesh networks is proposed in this article. The MRLR mechanism dismembers the multicast tree into several disjoint segment-blocks (sub-trees) and reserves preplanned spare capacity to set up multiple protection rings in each segment-block for providing rapid local recovery. The MRLR scheme outperforms other methodologies in terms of the blocking probability, recovery time, and average hop count of protection path per session for different network topologies.     

Scalable QoS-based IP multicast over label-switching wireless ATMnetworks

A Mobile IP multicast prototype that integrates a label-switching wireless asynchronous transfer mode, the mobile core-based multicast architecture, and an Internet multicast infrastructure is presented. MCOM creates multiple core-based layer 2 multicast trees that are independently established in member networks. They are interconnected via the Internet using layer 3 multicast routing. Gateways on the border of the Internet and wireless ATM networks convert ATM multicast traffic to suitable IP packets as well as converting from IP packets to ATM cells for MCOM. To solve the cell interleaving problem that results, ATM block transfer/immediate transmission capability is reasonably modified. Additionally, class-based block buffer management for ATM multicast connections is built into wireless ATM switches for soft quality of service control. Dynamic group management, multicast channel rerouting, and reliable multicasting are also studied in relation to existing Internet protocols like Mobile IP, Internet group management protocols, and multicast routing protocols     

Performance analysis of multicast routing and wavelength assignment protocol with dynamic traffic grooming in WDM networks

The need for on‐demand provisioning of wavelength‐routed channels with service‐differentiated offerings within the transport layer has become more essential because of the recent emergence of high bit rate Internet protocol (IP) network applications. Diverse optical transport network architectures have been proposed to achieve the above requirements. This approach is determined by fundamental advances in wavelength division multiplexing (WDM) technologies. Because of the availability of ultra long‐reach transport and all‐optical switching, the deployment of all‐optical networks has been made possible. The concurrent transmission of multiple streams of data with the assistance of special properties of fiber optics is called WDM. The WDM network provides the capability of transferring huge amounts of data at high speeds by the users over large distances. There are several network applications that require the support of QoS multicast, such as multimedia conferencing systems, video‐on‐demand systems, real‐time control systems, etc. In a WDM network, the route decision and wavelength assignment of lightpath connections are based mainly on the routing and wavelength assignment (RWA). The multicast RWA's task is to maximize the number of multicast groups admitted or minimize the call‐blocking probability. The dynamic traffic‐grooming problem in wavelength‐routed networks is generally a two‐layered routing problem in which traffic connections are routed over lightpaths in the virtual topology layer and lightpaths are routed over physical links in the physical topology layer. In this paper, a multicast RWA protocol for capacity improvement in WDM networks is designed. In the wavelength assignment technique, paths from the source node to each of the destination nodes and the potential paths are divided into fragments by the junction nodes and these junction nodes have the wavelength conversion capability. By using the concept of fragmentation and grouping, the proposed scheme can be generally applied for the wavelength assignment of multicast in WDM networks. An optimized dynamic traffic grooming algorithm is also developed to address the traffic grooming problem in mesh networks in the multicast scenario for maximizing the resource utilization and minimizing the blocking probability. Copyright © 2011 John Wiley & Sons, Ltd.     

Multicast service protection algorithm based on elastic optical network

With the rapid growth of the network traffic,the elastic optical network (EON) has been proposed as a promising solution due to its high spectrum efficiency and flexible bandwidth provision.Meanwhile,multicast routing and spectrum allocation,and the survivability of the network become more challenging than that in the conventional optical network.The routing for multicast traffic and its protection algorithm in EON was investigated.An integer linear programming (ILP) formulation with the objective to minimize total spectrum consumption was presented.In addition,a heuristic algorithm called multicast sub-tree protection algorithm (MSPA) to achieve sufficient protection and satisfy resources savings was designed.The simulation results demonstrate that comparing with the traditional multicast routing and protection algorithm,MSPA performs well in improving the blocking probability and the spectrum utilization of the network.     

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.     

Performance analysis of optical multicast in a new switching structure

The emergence of new services demands multicast function in optical network.Because of the high cost and complex architecture of multicast capable (MC) node, splitter-sharing switch structure is introduced in which the light splitters are shared by all input signals.To accommodate to this situation, by extending resource ReSerVation protocol-traffic engineering (RSVP-TE) and open shortest path first-traffic engineering (OSPF-TE), a new optical multicast mechanism is provided and the signaling flow and its finite state machine model are given.At the same time, a multicast routing algorithm in splitter-sharing optical network and a changing link weight policy to balance network traffic are proposed.Simulations in NSFNET show no matter with or without wavelength converters, when the number of splitters is 25% of that demanded by traditional MC nodes, the multicast performance has been close to the ideal circumstance.Wavelength converters and changing link weight help much in improving the traffic performance when the number of splitters is adequate.     

WDM网状网络中一种动态多播自适应业务疏导算法

光多播业务需要消耗大量的WDM光网络带宽资源,业务疏导是光多播网络降低业务请求阻塞率和提高带宽资源利用率的有效方法。提出了一种新型光多播疏导节点结构,研究了疏导端口优先的多播业务疏导算法(TGPFA)和新建光树优先的多播业务疏导算法(TCLFA),进而提出了一种能够适应网络资源变化的动态多播业务疏导算法(ADMGA)。结果表明,在网络资源有限的情况下,ADMGA算法能取得较低的请求阻塞率和带宽阻塞率,获得较好的网络性能。     

Performance Evaluation of Service‐Aware Optical Transport System

We propose and experimentally demonstrate a service‐aware optical transport system. The proposed service‐aware optical transport system makes a flow based on service type and priority of traffic. The generated flow is mapped to a corresponding sub‐λ for transport over an optical network. Using sub‐λ provided by the centralized control plane, we could effectively provide quality‐of‐service guaranteed Ethernet service and best‐effort service simultaneously in a single link. The committed information rate (CIR) traffic and best‐effort traffic are assigned to different sub‐λs. The bandwidth of the CIR traffic is guaranteed without being affected by violation traffic because the bandwidth is managed per each sub‐λ. The failure detection time and restoration time from a link failure is measured to be about 60 µs and 22 ms, respectively, in the ring network. The measured restoration time is much smaller than the 50 ms industry requirement for real‐time services. The fast restoration time allows the proposed service‐aware optical transport system to offer high availability and reliability which is a requirement for transport networks.     

Multicast protection scheme based on Hamiltonian cycle in fault-tolerant optical mesh networks

The increase of multimedia service requirements results in the growing popularity of the multicast in Wavelength-Division Multiplexing (WDM) optical mesh networks. Multicast fault tolerance in WDM optical mesh networks is an important issue because failures caused by the traffic carried in WDM optical mesh networks may lead to huge data loss. Previous works have proposed multicast protection algorithms to address the single-fiber link failure dominant in current optical mesh networks. However, these existing algorithms are all mainly based on path protection or segment protection, which may lead to long restoration times and complicated protection switching procedures. This paper therefore proposes a new heuristic algorithm, called Enhanced Multicast Hamiltonian Cycle Protection (EMHCP), in which all working light-trees of multicast demands can be protected by a Hamiltonian cycle in the network. For each multicast demand, EMHCP computes a least-cost light-tree based on the presented link-cost function that considers load balancing and proper straddling link selection so that backup wavelengths on the Hamiltonian cycle can be reduced. Simulation results show that EMHCP can obtain significant performance improvement compared with the conventional algorithm.     

Priority differentiated multicast flow scheduling method in Ceph cloud storage network

In order to solve the problem that existing flow scheduling method is difficult to meet the different multicast scheduling requirements of multi-service flows in the Ceph cloud storage network,a service priority-based multicast flow scheduling method was tailored.First,the network status was obtained via software defined network (SDN) to support flow scheduling.Then,a multicast task was decomposed into multiple attribute decision problems for multiple unicast path selection,and a method of unicast path selection based on technique for order preference by similarity to ideal solution (TOPSIS) was proposed.The unicast path selection method was used to find the optimal unicast path set for the service flow based on the flow’s network performance requirements.Then,the multicast distribution node was determined by the maximum common sub-path among the optimal unicast path sets for construct a multicast transmission path.The experiment results show that the proposed method can reduce the transmission delay of high priority flows while reduce the redundant traffic and better balance the traffic loads compared with the existing methods.     

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 ...     

On Multicast Routing for Wavelength-Routed WDM Networks with Dynamic Membership

Future broadband networks must support integrated services and offer flexible bandwidth usage. In our previous work in [1], we explored the optical link control (OLC) layer on the top of optical layer that enables the possibility of bandwidth on-demand (BoD) service directly over wavelength division multiplexed (WDM) networks. Today, more and more applications and services such as video-conferencing software and Virtual LAN service require multicast support over the underlying networks. Currently, it is difficult to provide wavelength multicast over optical switches without optical/electronic conversions although the conversion takes extra cost. In this paper, based on the proposed wavelength router architecture (equipped with ATM switches to offer O/E and E/O conversions when necessary), a dynamic multicast routing algorithm is proposed to furnish multicast services over WDM networks. The goal is to join a new group member into the multicast tree so that the cost, including the link cost and the optical/electronic conversion cost, is kept as low as possible. The same algorithm can be applied to other wavelength routing architectures with redefinition of electronic copy cost. The effectiveness of the proposed wavelength router architecture as well as the dynamic multicast algorithm is evaluated by simulation.     

Tree-shared multicast in optical burst-switched WDM networks

In this paper, we propose a new multicast scheme called tree-shared multicasting (TS-MCAST) in optical burst-switched wavelength-division-multiplexing networks, taking into consideration overheads due to control packets and guard bands (GBs) associated with data bursts. In TS-MCAST, multicast traffic belonging to multiple multicast sessions from the same source-edge node to possibly different destination-edge nodes can be multiplexed together in a data burst, which is delivered via a shared multicast tree. To support TS-MCAST, we propose three tree-sharing strategies based on equal coverage, super coverage, and overlapping coverage, and present a simple shared multicast tree-construction algorithm. For performance comparison, we consider two other multicast schemes: separate multicasting (S-MCAST) and multiple unicasting (M-UCAST). We show that TS-MCAST outperforms S-MCAST and M-UCAST in terms of bandwidth consumed and processing load (i.e., number of control packets) incurred for a given amount of multicast traffic under the same unicast traffic load with static multicast sessions and membership.     

Algorithms for multicast traffic grooming in WDM mesh networks

Several of the new applications in high-performance networks are of the multicast traffic type. Since such networks employ an optical network infrastructure, and since most of these applications require subwavelength bandwidth, several streams are usually groomed on the same wavelength. This article presents an account of recent advances in the design of optical networks for multicast traffic grooming in WDM mesh networks. The article addresses network design and session provisioning under both static and dynamic multicast traffic. Under static traffic conditions, the objective is to accommodate a given set of multicast traffic demands, while minimizing the implementation cost. Optimal and heuristic solution techniques for mesh network topologies are presented. Under dynamic traffic conditions, techniques for dynamic routing and session provisioning of multicast sessions whose objective is to minimize session blocking probabilities are explained. The article also presents a number of open research issues     

Recursive copy generation for multicast ATM switching

This paper describes the structure of a multicast asynchronous transfer mode (ATM) switching node employing a recursive copy generation algorithm, based on a self-routing network with a limited copying capability and a few added elements. With the network generates only a few copies a time of an input multicast cell, the remaining are obtained by recycling the output copies to the corresponding inputs as many times as necessary. The proposed recursive copy generation is also suitable to dynamically include new destinations and to delete old ones. The performance of the proposed structure, that has been implemented in a test-bed prototype, is also evaluated in terms of throughput and delay, via computer simulation, showing a possible performance improvement for multicast traffic with respect to an equivalent unicast input traffic. The cell loss probability in such structure is also evaluated     

Multicast with a new switching structure in optical networks

The emergence of new services demands for a multicast function in optical networks. At the same time, wavelength converters are introduced to increase the efficiency of wavelength usage. It is because of the high cost and complex architecture of optical multicast and wavelength conversion technology, that a new switch structure is introduced, in which optical splitters and wavelength converters are shared per-node. In order to accommodate this architecture, a multicast routing and wavelength assignment algorithm in a splitter–converter-sharing optical network and a changing link weight policy to balance network traffic are proposed. By extending RSVP-TE (Resource ReSerVation Protocol-Traffic Engineering) and OSPF-TE (Open Shortest Path First-Traffic Engineering), an optical multicast mechanism is provided, and message type, signaling flow, and finite state machine model are given. Simulations of NSFNET show that, when the number of splitters and converters are 50% and 12.5% of the full equipment respectively, the performance is close to the ideal case. Using a changing link weight policy can improve performance greatly, when there are enough splitters and converters.     

Multicast routing and bandwidth dimensioning in overlay networks

Multicast services can be provided either as a basic network service or as an application-layer service. Higher level multicast implementations often provide more sophisticated features and can provide multicast services at places where no network layer support is available. Overlay multicast networks offer an intermediate option, potentially combining the flexibility and advanced features of application layer multicast with the greater efficiency of network layer multicast. In this paper, we introduce the multicast routing problem specific to the overlay network environment and the related capacity assignment problem for overlay network planning. Our main contributions are the design of several routing algorithms that optimize the end-to-end delay and the interface bandwidth usage at the multicast service nodes within the overlay network. The interface bandwidth is typically a key resource for an overlay network provider, and needs to be carefully managed in order to maximize the number of users that can be served. Through simulations, we evaluate the performance of these algorithms under various traffic conditions and on various network topologies. The results show that our approach is cost-effective and robust under traffic variations.     

A Weighted Scheduling Mechanism to Reduce Multicast Packet Loss in IPTV Service over EPON

This letter proposes a weighted scheduling mechanism for Internet protocol television (IPTV) to improve the loss performance of multicast transmission over an Ethernet passive optical network (EPON). We propose a new weight policy from the number of multicast receivers to proportionally allocate the downstream bandwidth of IPTV traffic. The proposed mechanism is used in an optical line terminal to decrease lost packets of favorite IPTV services because the lost multicast packets are proportional to the number of receivers. The total proportion of lost multicast packets is reduced by up to 73% in an EPON.