Multicast Tree Research Articles

Efficient Communication Scheduling for Parameter Synchronization of DML in Data Center Networks

It's common practice to speed up machine learning (ML) training by distributing it across a cluster of computing nodes. Data-parallel distributed ML (DML) training relieves the pressure of computing node; however, the communication traffic introduced during parameter synchronization becomes bottleneck of DML training. Regarding communication bottleneck, we identify two primary causes: high contention of concurrent communication and large volume of redundant transmission in the push and pull stage while synchronizing parameters. To address these issues, we propose a novel Group Stale Synchronous Parallel (GSSP) scheme, which divides the nodes into groups and coordinates groups to synchronize in a circular order. GSSP mitigates network contention and is proven to converge. We provide analysis of the optimal group's number based on bandwidth and buffer size. For reducing traffic redundancy, we propose a multicast-based scheme, which generates multicast trees by minimizing links overlap and allocates transmission rate to multicast flows by solving the min-max optimization problem. Finally, we conduct extensive simulations to evaluate the performance of our proposals. We simulate parameter transmission of All-Reduce and parameter server in Fat-Tree with traffics trace of ML models. Simulation results show that our proposals provide communication-efficiency for DML training by mitigating contention and reducing redundancy.

OSCAR: On Optimizing Resource Utilization in Live Video Streaming

Live video streaming traffic and related applications have experienced significant growth in recent years. However, this has been accompanied by some challenging issues, especially in terms of resource utilization. Although IP multicasting can be recognized as an efficient mechanism to cope with these challenges, it suffers from many problems. Applying software-defined networking (SDN) and network function virtualization (NFV) technologies enable researchers to cope with IP multicasting issues in novel ways. In this article, by leveraging the SDN concept, we introduce OSCAR (Optimizing reSourCe utilizAtion in live video stReaming) as a new cost-aware video streaming approach to provide advanced video coding (AVC)-based live streaming services in the network. In this article, we use two types of virtualized network functions (VNFs): virtual reverse proxy (VRP) and virtual transcoder function (VTF). At the edge of the network, VRPs are responsible for collecting clients’ requests and sending them to an SDN controller. Then, by executing a mixed-integer linear program (MILP), the SDN controller determines a group of optimal multicast trees for streaming the requested videos from an appropriate origin server to the VRPs. Moreover, to elevate the efficiency of resource allocation and meet the given end-to-end latency threshold, OSCAR delivers only the highest requested quality from the origin server to an optimal group of VTFs over a multicast tree. The selected VTFs then transcode the received video segments and transmit them to the requesting VRPs in a multicast fashion. To mitigate the time complexity of the proposed MILP model, we present a simple and efficient heuristic algorithm that determines a near-optimal solution in polynomial time. Using the MiniNet emulator, we evaluate the performance of OSCAR in various scenarios. The results show that OSCAR surpasses other SVC- and AVC-based multicast and unicast approaches in terms of cost and resource utilization.

Q-Learning and MADMM Optimization Algorithm Based Interference Aware Channel Assignment Strategy for Load Balancing in WMNS

Wireless Mesh Networks (WMNs) have been considered one of the main technologies for configuring wireless machines since they appeared. In a WMN, wireless routers provide multi-hop wireless connectivity between hosts on the network and allow access to the internet through the gateway routers. These wireless routers are normally equipped with the multiple radios in the wireless mesh network that operate on multiple channels with the multiple interference, which is caused to reduce the network performance and end-to-end delay. In this paper, we proposed an efficient optimization algorithm to solve the channel assignment problem which cause due to the multichannel multiradios in WMN’s. The main objective of our paper is to minimize the channel interference among networked devices. So, initially we construct a multicast tree with minimum interference by using Q-Learning algorithm, which is helps to minimize the end-to-end delay of packet delivery. From the constructed multicast tree, we intend to develop a channel assignment strategy with the minimum interference by using Modified version of Alternative Direction Method of Multipliers (MADMM) optimization algorithm, which is helps to increase the network throughput and packet delivery ratio. The proposed strategy was implemented by using NS-2 (Network Simulator-2) and the experimental result show that the performance of the proposed method is very high compared to the other method and the performance was calculated by using the feature metrics such as average throughput, packet delivery ratio, end-toend delay and total cost, which is compared with the other existing channel assignment strategies such as Learning Automata and Genetic Algorithm (LA-GA), GA-based approach, link-channel selection and rate-allocation (LCR) and learning automata based multicast routing (LAMR) channel assignment methods.

Optimal relay and channel selection schemes for multiconstrained QoS multicast routing in cognitive radio ad hoc networks

SummaryDuring multicasting in cognitive radio ad hoc network (CRAHN), apart from energy consumption, interchannel interference, path delay, and channel switching delay should be minimized. The channel selection should be done, based on spectrum opportunities and channel quality. Hence, the multicast routing problem becomes a multiconstrained QoS routing problem. This paper proposes optimal relay and channel selection schemes (ORCS) for multiconstrained QoS multicast routing in CRAHNs. For multicast tree construction, distributed minimum spanning tree (DMST) is used. For meeting the delay, energy, and interference constraints, relay nodes are chosen with minimum path delay, less energy consumption, and minimum interference. For effective channel assignment, channels with good channel quality, maximum spectrum accessibility, and sufficient common slots are selected. By simulation results, it has been shown that the proposed ORCS minimize the energy consumption and end‐to‐end delay.

An Identifier and Locator Decoupled Multicast Approach (ILDM) Based on ICN

Many bandwidth-intensive applications (such as online live, online games, etc.) are more suitable for using multicast to transmit information. Due to the advantages in scalability, Shared Tree (ST) is more suitable for large-scale deployment than Source-Based Tree (SBT). However, in ST-based multicast, all multicast sources need to send multicast data to a center node called a core, which will lead to core overload and traffic concentration. Besides, most existing multicast protocols use the shortest path between the source or the core and each receiver to construct the multicast tree, which will result in traffic overload on some links. In this paper, we propose an Identifier and Locator Decoupled Multicast approach (ILDM) based on Information-Centric Networking (ICN). ILDM uses globally unique names to identify multicast services. For each multicast service, the mapping between the multicast service name and the addresses of multicast tree nodes is stored in the Name Resolution System (NRS). To avoid core overload and traffic aggregation, we presented a dynamic core management and selection mechanism, which can dynamically select a low-load core for each multicast service. Furthermore, we designed a path state-aware multicast tree node selection mechanism to achieve traffic load balancing by using low-load links more effectively. Experimental results showed that our proposed multicast approach outperformed some other multicast methods in terms of core load, number of join requests, link load, traffic concentration, and routing state.

Delay-Optimized Multicast Tree Packing in Software-Defined Networks

In traditional networks, the multicast tree packing solutions usually aim to minimize the overall multicast tree cost, which can effectively improve network accommodation capacity but is disadvantageous to fully use network resources. In this paper, we propose a delay-optimized multicast tree packing problem called delivery delay minimized multicast tree packing (DDMMTP), which aims to minimize the average source-destination delay, under constraints on the bandwidth and maximum source-destination delay, according to available network resources. A low source-destination delay is desirable because it improves the service quality, especially for time-sensitive applications. In practice, the DDMMTP is highly valuable for the software-defined network (SDN) mainly because this new network paradigm has the ability to rapidly rearrange multicast routes on demand. The DDMMTP problem is NP-hard. We solve it approximately by a batched multicast tree packing algorithm and a network accommodation capacity improvement algorithm that adjusts existing multicast paths on demand. We also propose a source-destination delay improvement algorithm to further reduce source-destination delays based on new available network resources.

A New Deep Q-Network Design for QoS Multicast Routing in Cognitive Radio MANETs

In this paper, we propose a new deep Q-network (DQN) design for quality-of-service (QoS) multicast routing (DQMR) protocol to establish efficient QoS multicast (EQM) trees in cognitive radio mobile ad hoc networks (CR-MANETs). An EQM tree is a shortest-path multicast tree with minimum end-to-end (E2E) cost (a combination of queuing size ratio and link stability) subject to QoS constraints such as queuing size ratio, link stability, number of hops, number of time slots and avoiding the licensed channel of primary users. Particularly, we propose an NP-complete optimization problem such that its feasible solution is an EQM tree. To address this problem, we design a new DQN model and a new game-based model to form EQM trees in real-time by offline training instead of online training as done in previous papers. Moreover, the DQMR protocol is also guaranteed to have high stability, low routing delay, low control overhead, and high packet delivery ratio (PDR). Furthermore, one more new contribution of the paper is that exact closed-form expressions for the E2E queuing delay of a multicast routing tree are also derived assuming random waypoint mobility and the reference point group mobility models to compare with simulation results of routing delay. Simulation results show that the DQMR protocol outperforms multicast ad hoc on-demand distance vector routing protocol in terms of routing delay, control overhead, and PDR.

Solving the Delay-Constrained Least-Cost routing problem using Tabu Search with Edge Betweenness

Multicast routing consists of concurrently sending the same information from a source to a subset of all possible destinations in a computer network thus becomes an important technology communication. To solve the problem, a current approach for efficiently supporting a multicast session in a network consists of establishing a multicast tree that covers the source and all terminal nodes. This problem can be reduced to a minimal Steiner tree problem (MST) which aims to look for a tree that covers a set of nodes with a minimum total cost, the problem is NP-hard. In this paper, we investigate metaheuristics approaches for the Delay-Constrained Least-Cost (DCLC) problem, we propose a novel algorithm based on Tabu Search procedure with the Edge Betweenness (EB). The EB heuristic used first to improve KMB heuristic, able to measure the edge value to being included in a given path. The obtained solution improved using the tabu search method. The performance of the proposed algorithm is evaluated by experiments on a number of benchmark instances from the Steiner library. Experimental results show that the proposed metaheuristic gives competitive results in terms of cost and delay compared to the optimal results in Steiner library and other existing algorithms in the literature.

Решение проблемы обеспечения качества дерева многоадресной рассылки услуг

This article presents a flow-based mixed integer programming formulation for the Quality of Service Multicast Tree problem. This is a relevant problem related to nowadays telecommunication networksto distribute multimedia over cloud-based Internet systems. To the best of our knowledge, no previous mixed integer programming formulation was proposed for Quality of Service Multicast Tree Problem. Experimental evaluation is performed over a set of realistic problem instances from SteinLib, to prove that standard exact solvers can find solutions to real-world size instances. Exact method is applied for benchmarking the proposed formulations, finding optimal solutions and low feasible-to-optimal gaps in reasonable execution times.

Coded-MPMC: One-to-Many Transfer Using Multipath Multicast With Sender Coding

One-to-many transfers in a fast and efficient manner are essential to meet the growing need for duplicating, migrating, or sharing bulk data among servers in a datacenter and across geographically distributed datacenters. Some existing works utilize multiple multicast trees for a one-to-many transfer request to increase network link utilization and its transfer throughput. However, since those schemes do not fully utilize the max-flow value of transmission from a single sender to each recipient, there is room for each recipient to retrieve data more quickly. Therefore, assuming fully-controlled networks with full-duplex links, we pose a problem to find a set of multicast flows with an allocation of block-wise transmissions by which each of multiple recipients with diverse max-flow values from the sender can utilize its own max-flow value. Based on that, assuming a sender-side coding capability on file blocks, we design a schedule of block transmissions over multiple phases by which each recipient can achieve a lower-bound of its file retrieval completion time, i.e., the file size divided by its own max-flow value. This paper presents the coded Multipath Multicast (Coded-MPMC) for one-to-many transfers with heuristic procedures to find a desired set of multicast flows on which block transmissions are scheduled. Through extensive simulations on large-scale real-world network topologies and different types of randomly-generated synthetic topologies, the proposed method is shown to design a desired schedule efficiently. A preliminary implementation on OpenFlow is also reported to show the fundamental feasibility of Coded-MPMC.

Mixed Integer Programming Formulations for Steiner Tree and Quality of Service Multicast Tree Problems

This article presents flow-based mixed integer programming formulations for the Steiner Tree Problem and its variant applied to model and solve the Quality of Service Multicast Tree problem. This is a relevant problem related to nowadays telecommunication networks, particularly Content Delivery Networks, to distribute multimedia over cloud-based Internet systems. To the best of our knowledge, no previous mixed integer programming formulation was proposed for the Quality of Service Multicast Tree problem variant. Experimental evaluation is performed over a set of realistic problem instances from SteinLib, a reference test-set repository, modified accordingly to prove that standard exact solvers are capable of finding solutions to real-world size instances. Exact methods are applied for benchmarking the proposed formulations, finding optimal solutions and low feasible-to-optimal gaps in reasonable execution times.

Multicast Routing Model to Minimize Number of Flow Entries in Software-Defined Network

Software-defined network (SDN) is a network that the centralized SDN controller stores flow entries in the flow table of each SDN switch and controls packet flows as instructed by the stored flow entries. When a multicast service is provided in an SDN, the SDN controller stores a multicast entry dedicated for a multicast group in each SDN switch. It is necessary to suppress the number of flow entries required to set up a multicast tree due to the limited capacity of the flow table. In a conventional research, a multicast routing model that suppresses the number of multicast entries in one multicast request by replacing a part of them with unicast entries has been devised. However, since this conventional model individually determines a multicast tree route for each request, unicast entries configured for the same receiver are distributed in various SDN switches when multiple multicast services are requested. As a result, there is still the possibility of improving the reduction of the number of flow entries. In this paper, we propose a multicast routing model for multiple multicast requests that minimizes the number of flow entries. This proposed model determines multiple multicast tree routes simultaneously so that a unicast entry configured for the same receiver and stored in the same SDN switch is shared by multicast trees. We formulate the proposed model as an Integer Linear Programming (ILP) problem. Numerical results show that the proposed model reduces the required number of flow entries compared to the conventional model.

Dynamic multicast sharing protection algorithm based on fuzzy game in multi-domain optical network

Aiming at the problem of dynamic multicast service protection in multi-domain optical network, this paper proposes a dynamic multicast sharing protection algorithm based on fuzzy game in multi-domain optical network. The algorithm uses the minimum cost spanning tree strategy and fuzzy game theory. First, it virtualizes two planes to calculate the multicast tree and the multicast protection tree respectively. Then, it performs a fuzzy game to form a cooperative alliance to optimize the path composition of each multicast tree. Finally, it generates a pair of optimal multicast work tree and multicast protection tree for dynamic multicast services. The time complexity of the algorithm is O(k3m2n), where n represents the number of nodes in the networks, k represents the number of dynamic multicast requests, and m represents the number of destination nodes for each multicast request. The experimental results show that the proposed algorithm reduces significantly the blocking rate of dynamic multicast services, and improves the utilization of optical network resources within a certain number of dynamic multicast request ranges.

Multicast routing strategy for SDN-cluster based MANET

The energy limitation and frequent movement of the mobile Ad hoc network (MANET) nodes (i.e., devices) make the routing process very difficult. The multicast routing problem is one of the NP-complete problems. Therefore, the need for a new power-aware approach to select an optimum multicast path with minimum power consumption that can enhance the performance and increase the lifetime of MANET has become urgent. Software defined network (SDN) is a new technique that can solve many problems of the traditional networks by dividing the architecture into data part and control part. This paper presents three power-aware multicast routing strategies for MANET. First one called a Reactive Multicast routing strategy for cluster based MANET by using SDN (RMCMS), second one called proactive multicast routing strategy for cluster based MANET by using SDN (PMCMS) and third one represents modification of PMCMS called M-PMCMS. Moreover, it produces a new mathematical model to build a multicast tree with minimum power consumption and takes into account the remaining power in each node. All proposed multicast strategies operate based on this mathematical model and aim to maximize the MANET lifetime by exploiting the advantages of SDN and clustering concepts. They consider the multicast tree with minimum power consumption as an optimal one. The simulation results illustrated that RMCMS is better than PMCMS, M-PMCMS, and MAODV in terms of power consumption and network overhead while M-PMCMS is the best one in terms of dropped packets ratio (DPR) and average end to end (E2E) delay.

Reliability provision in software defined power substations communication networks

In past years, the growing complexity of the electrical system and the rise in the number of Intelligent Electronic Devices (IEDs) have increased the data network management complexity in power substations. A pressing need to improve the reliability of such environments has pushed energy companies to increase the investment in the operation of their communication networks. This paper proposes to use the Software Defined Networking (SDN) paradigm into the communication networks of power substations to implement novel redundancy techniques based on redundant multicast trees, in order to replace the traditional redundancy mechanisms in power substation communication networks resulting in capital and operational costs reduction. We apply pre-planned protection based on redundant trees and formulate an Integer Linear Programming (ILP) model to provide redundant multicast trees in the network trying to minimize the number of used network links. Redundant trees transmit duplicate traffic under the same underlying LAN in isolation, to guarantee zero recovery time and improve the use of network resources. Simulation results show that our approach achieves the same performance as traditional redundancy mechanisms using half of the network resources (i.e., compared against the Parallel Redundancy Protocol, PRP).

Improving acceptance rate of QoS-guaranteed point-to-multipoint traffic flows in elastic optical networks

Abstract This paper studies the load-balanced routing and admission control for point-to-multipoint traffic flows in elastic optical networks (EONs). EONs have emerged as a promising technology to provide high capacity for next-generation networks. Elastic bandwidth allocation promotes the spectrum utilization efficiency. We consider the problem of constructing bandwidth-guaranteed trees for on-demand point-to-multipoint session requests. A request is accepted, if a multicast tree with sufficient bandwidth on each link can be established. The main objective is to increase the multicast acceptance rate in the network. For this purpose, we propose an efficient scheme, namely optical load-balanced multicast routing with admission control (OLMR-AC), to improve the wavelength resources utilization in the network. As an advantage, OLMR-AC jointly considers both distance and congestion factors to create a multicast session. For each admitted session, a bandwidth–guaranteed steiner tree is provided in which not only the source node has a minimum-cost path to each receiver, but also its overall cost is minimal. The proposed scheme distributes the on-demand traffic flows over the available links fairly. Simulation results show the efficiency of the OLMR-AC algorithm in terms of multicast acceptance rate, average length of lightpaths, throughput, number of transmissions, and load variance.

New algorithm of multi-strategy channel allocation for edge computing

Wireless mesh networks (WMNs) are a kind of wireless network technology that can transmit multi-hop information, and have been regarded as one of the key technologies for configuring wireless machines. In WMNs, wireless routers can provide multi-hop wireless connections between nodes in the network and access the Internet through gateway devices. Multicast is a communication technology that uses best effort to send information from a source node to multiple destinations. In this paper, we study the problems of channel interference and time slot multi-user collisions caused by radio during WMNs information transmission. Through innovative use of edge computing technology to construct a node data cache model and step-by-step calculation of node channel separation, a multi-strategy channel allocation algorithm for edge computing is proposed. The mechanism of this algorithm is to use edge computing technology to pre-store the data in the nodes in the multicast tree and calculate the channel separation between the nodes, and then select the transmission channel number of the node with the least interference to avoid mutual interference between node information transmissions. Through experimental tests and comparisons, the MSCA (Multi-Strategy Channel Allocation algorithm for edge computing) algorithm presented in this paper can minimize channel interference and overall network energy consumption while satisfying throughput and end-to-end delay.

Efficient File Dissemination in Data Center Networks With Priority-Based Adaptive Multicast

In today’s data center networks (DCN), cloud applications commonly disseminate files from a single source to a group of receivers for service deployment, data replication, software upgrade, etc. For these group communication tasks, recent advantages of software-defined networking (SDN) provide bandwidth-efficient ways—they enable DCN to establish and control a large number of explicit multicast trees on demand. Yet, the benefits of data center multicast are severely limited, since there does not exist a scheme that could prioritize multicast transfers respecting the performance metrics wanted by today’s cloud applications, such as pursuing small mean completion times or meeting soft-time deadlines with high probability. To this end, we propose PAM (Priority-based Adaptive Multicast), a preemptive, decentralized, and ready-deployable rate control protocol for data center multicast. At the core, switches in PAM explicitly control the sending rates of concurrent multicast transfers based on their desired priorities and the available link bandwidth. With different policies of priority generation, PAM supports a range of scheduling goals. We not only prototype PAM upon the emerged P4-based programmable switch with novel approximation designs, but also evaluate its performance with ns3-based extensive simulations. Results imply that PAM is ready-deployable; it converges very fast, has negligible impacts on coexisting TCP traffic, and always performs near-optimal priority-based multicast scheduling.

Smart-Green-Mult (SGM): overhear from topological kingpins in software defined wireless sensor networks

Wireless sensor networks (WSNs) are an important component of the Internet of Things (IoT). Each multicast group in a WSN consists of a set of multicast members. In a sparse network, multicast members belonging to the same group may not be very closely spaced. On the other hand, in a dense environment, more than one multicast member of a group may highly reside within downlink regions of the same router which may or may not be a multicast member. In that case, a multicast message can be delivered to more than one multicast member in a shot. This characteristic improves the status of a node from an ordinary router to a topological kingpin. If a good number of topological kingpins are included in a multicast tree, then a great amount of energy is saved increasing network throughput. The present article proposes one such energy efficient multicast scheme: Smart–Green–Mult (SGM), based on Software Defined Wireless Sensor Network (SD-WSN) framework. The network is divided into several zones. The shape of each zone is either circular or elliptical or polygonal. Each zone is under control of an Software Defined Network controller. SDN controller of each zone is aware of the topology of the zone and can compute energy efficient paths from any source to any destination inside or outside the zone. Overall this is a multicast protocol in SD-WSN.

MRCSC: A cross-layer algorithm for joint Multicast Routing, Channel selection, Scheduling, and Call admission control in multi-cell multi-channel multi-radio cognitive radio wireless networks

This paper addresses the problem of joint multicast routing, channel selection, scheduling, and call admission control in multi-cell multi-channel multi-radio cognitive radio wireless mesh networks. The applied model relies on the QoS sessions, where each one is expressed with a bandwidth requirement. We propose a cross-layer algorithm named “Multicast Routing, Channel selection, Scheduling, and Call admission control (MRCSC)”. The proposed scheme, considering wireless broadcast advantage, channel/radio diversity, and spatial reuse, uses both intra- and inter-cell relaying to create multicast trees with a specific bandwidth. MRCSC considers both inter-flow and intra-flow interferences. It adopts an efficient collision-free mechanism to greedily schedule different multicast transmission in the network. As an advantage, considering the multi-radio technology, MRCSC allows the nodes to simultaneously send/receive data on different available non-overlapping channels. Numerical results of our comprehensive simulations confirm the efficiency of the MRCSC algorithm in terms of the number of transmissions, stability, and multicast period.