Shared Tree Research Articles

Core Selection to Solve Multicast Routing with Delay and Delay-Variation Constraints

The basis of multicast data transmission is to construct a multicast tree. The main problem concerning the construction of a multicast tree is the selection of the root of the shared tree or the core point. Therefore, the algorithm we propose guarantees that the delay from the source to any destination does not exceed a real-time constraint satisfying the delay-variation constraint under cost minimization. The core selection function in this algorithm achieves a balance of optimizing cost and delay of the multicast tree. Simulation results show that the algorithm has low complexity and balances between the computational complexity and performance.

基于多核点共享树的多源光组播路由方法

Network coding was introduced to optimize the selection of multi-core nodes and transmission of multicast information.A method was proposed to construct optical multicast routing based on multi-core node shared tree and network coding to decrease the wavelength consumption and to improve the performance of network load balance.The network coding candicate core node set was produced by deleting the nodes which lead to the source node bypass loop.The network coding core nodes of multisource shared trees were determined by utilizing the heuristic matrix operation to achieve the minimal core nodes covering the maxmial source nodes.Then,the network coding was applied to transmit the information between the core nodes and destination nodes to reduce the wavelength consumption.And,the wavelength assignment and edge disjoint path were discussed for the multi-core node shared tree.Comparing with the multicast routing with single-core shared trees and singel-core shared trees based on the network coding,the simulation results show that the multicast routing with multi-core node shared trees based on network coding can get the least required wavelenght and achieve the best performance of network load balance.

基于多核点共享树的多源光组播路由方法

Network coding was introduced to optimize the selection of multi-core nodes and transmission of multicast information.A method was proposed to construct optical multicast routing based on multi-core node shared tree and network coding to decrease the wavelength consumption and to improve the performance of network load balance.The network coding candicate core node set was produced by deleting the nodes which lead to the source node bypass loop.The network coding core nodes of multisource shared trees were determined by utilizing the heuristic matrix operation to achieve the minimal core nodes covering the maxmial source nodes.Then,the network coding was applied to transmit the information between the core nodes and destination nodes to reduce the wavelength consumption.And,the wavelength assignment and edge disjoint path were discussed for the multi-core node shared tree.Comparing with the multicast routing with single-core shared trees and singel-core shared trees based on the network coding,the simulation results show that the multicast routing with multi-core node shared trees based on network coding can get the least required wavelenght and achieve the best performance of network load balance.

Performance Evaluation of DVMRP Multicasting Network over ICMP Ping Flood for DDoS

The Paper evaluates the performance of Bi-directional Shared Tree (BST) multicasting network with two sources and four receivers, attacked by five attackers. These attackers attack the source 1 in network by ICMP Ping Flood. Here we execute the simulation and draw network throughput between source 1 and source 2, queuing transmission delay and drop out data packets at source 1 for ping packet of size 16, 64 and 96 Bytes for 500, 1500 and 2500 ping packets per second. The simulation results indicate that throughput decreases with the increase in attack packet size and attack intensity, and remain constant for all values of intensity with larger packet size, delay increases with increase in attack packet size and decrease with increase in attacking intensity. Also, with the increase in attack packet size the number of dropped packets remain nearly same for different intensities.

Dual Decomposition for Computational Optimization of Minimum-Power Shared Broadcast Tree in Wireless Networks

We consider the problem of constructing a shared broadcast tree (SBT) in wireless networks, such that the total power required for supporting broadcast initiated by all source nodes is minimal. In the well-studied minimum-energy broadcast (MEB) problem, the optimal tree varies by source. In contrast, SBT is source-independent, thus substantially reducing the overhead for information storage and processing. The SBT problem also differs from the range assignment problem (RAP), because the power for message forwarding in SBT, although being source-independent, depends on from which tree neighbor the message is received. We approach SBT from a computational optimization standpoint, and present a dual decomposition method applied to an optimization model that embeds multiple directed trees into a shared tree. For the dual decomposition method, some of the constraints in the model are preferably formulated implicitly. The dual decomposition scheme is coupled with a fast local search algorithm. We report computational results demonstrating the effectiveness of the proposed approach. In average, the performance gap to global optimality is less than three percent.

QoS Supported IPTV Service Architecture over Hybrid-Tree-Based Explicit Routed Multicast Network

With the rapid advance in multimedia streaming and multicast transport technology, current IP multicast protocols, especially PIM-SM, become the major channel delivery mechanism for IPTV system over Internet. The goals for IPTV service are to provide two-way interactive services for viewers to select popular program channel with high quality for watching during fast channel surfing period. However, existing IP multicast protocol cannot meet above QoS requirements for IPTV applications between media server and subscribers. Therefore, we propose a cooperative scheme of hybrid-tree based on explicit routed multicast, called as HT-ERM to combine the advantages of shared tree and source tree for QoS-supported IPTV service. To increase network utilization, the constrained shortest path first (CSPF) routing algorithm is designed for construction of hybrid tree to deliver the high-quality video stream over watching channel and standard quality over surfing channel. Furthermore, the Resource Reservation Protocol- Traffic Engineering (RSVP-TE) is used as signaling mechanism to set up QoS path for multicast channel admission control. Our simulation results demonstrated that the proposed HT-ERM scheme outperforms other multicast QoS-based delivery scheme in terms of channel switching delay, resource utilization, and blocking ratio for IPTV service.

Covert Flow Graph Approach to Identifying Covert Channels

In this paper, the approach for identifying covert channels using a graph structure called Covert Flow Graph is introduced. Firstly, the construction of Covert Flow Graph which can offer information flows of the system for covert channel detection is proposed, and the search and judge algorithm used to identify covert channels in Covert Flow Graph is given. Secondly, an example file system analysis using Covert Flow Graph approach is provided, and the analysis result is compared with that of Shared Resource Matrix and Covert Flow Tree method. Finally, the comparison between Covert Flow Graph approach and other two methods is discussed. Different from previous methods, Covert Flow Graph approach provides a deep insight for system’s information flows, and gives an effective algorithm for covert channel identification.

A Heuristic Algorithm for Core Selection in Multicast Routing

With the development of network multimedia technology, more and more real-time multimedia applications need to transmit information using multicast. The basis of multicast data transmission is to construct a multicast tree. The main problem concerning the construction of a shared multicast tree is selection of a root of the shared tree or the core point. In this paper, we propose a heuristic algorithm for core selection in multicast routing. The proposed algorithm selects core point by considering both delay and inter-destination delay variation. The simulation results show that the proposed algorithm performs better than the existing algorithms in terms of delay variation subject to the end-to-end delay bound. The mathematical time complexity and the execution time of the proposed algorithm are comparable to those of the existing algorithms.

Comparison and Analysis of PIMDM and BST Multicasting Network over Drop Tail Queuing Technology

The paper contrast a Multicasting network using PIM-DM (Protocol Independent Multicast - Dense Mode) with BST (BiDirectional Shared Tree) protocol using NS2. The networking topology is well analyzed for two sources and drop of data packet and throughput is recorded and drawn. The simulation results mark the decrease in drop out packets for BST by 55.88235% on node 0 and some increase in drop out packets at node 1.

A Depth-optimal Low-complexity Distributed Wireless Multicast Algorithm

This paper presents a wireless multicast tree construction algorithm, SWIM (Source-initiated WIreless Multicast). SWIM constructs a tree on which each multicast destination has the minimum possible depth (number of hops from the nearest source). It is proved that SWIM is fully distributed, with a worst case complexity upper-bounded by O(N3), and an empirically found average complexity of only O(N2). SWIM forms one shared tree from source(s) to the multicast destinations; yet, as a by-product, it creates a multicast mesh structure by maintaining alternative branches at every tree node, thus providing robustness to link failures. This makes it suitable for both ad hoc networks and access networks with multiple gateways. In terms of minimizing the number of forwarding nodes, SWIM is optimal for unicast and competitive with the state of the art for multicast, outperforming the best known distributed approaches from the literature except for the multicast ad hoc on demand distance vector (MAODV) algorithm. However, simulations of the MAODV algorithm alongside SWIM on a large set of network instances show that the depth minimality of SWIM leads to lower average delay per multicast destination. It is also shown that the delay performance of SWIM is virtually unaffected by the presence of low mobility in the network.

Scalable and Robust Location Aware Multicast Algorithm (SRLAMA) for MANET

An ad hoc network is composed of mobile nodes without the intervention of any fixed infrastructure or central administration. Multicasting is intended for group-oriented communication. A lot many applications depend on one-to-many or many-to-many dissemination of the information. However, in ad hoc environment, multicasting protocols are faced with the challenge of producing multihop routes under dynamic topology and bandwidth constraints. Due to the dynamic topology of MANETs it is very difficult to build optimal multicast trees and maintaining group membership, making even more challenging to implement scalable and robust multicast in Mobile Ad hoc Networks (MANET). A Scalable and Robust Location Aware Multicast Algorithm, called SRLAMA, for mobile ad hoc networks is presented in the paper that is based on creation of shared tree using the physical location of the nodes for the multicast sessions. It constructs a shared bi-directional multicast tree with an alternate root that avoids the network partitioning in case of primary root failurte, which results in better performance even than a shared tree. The algorithm uses the concept of small overlapped zones around each node for employing proactive routing with in the smaller zone. Protocol is based on the location information obtained employing relevant data structure, which effectively reduces the overheads for route searching and shared multicast tree maintenance. It employs a preventive route reconfiguration to avoid the latency in case of link breakages and to prevent the network from splitting.

Initial Algebra Semantics for Cyclic Sharing Tree Structures

Terms are a concise representation of tree structures. Since they can be naturally defined by an inductive type, they offer data structures in functional programming and mechanised reasoning with useful principles such as structural induction and structural recursion. However, for graphs or "tree-like" structures - trees involving cycles and sharing - it remains unclear what kind of inductive structures exists and how we can faithfully assign a term representation of them. In this paper we propose a simple term syntax for cyclic sharing structures that admits structural induction and recursion principles. We show that the obtained syntax is directly usable in the functional language Haskell and the proof assistant Agda, as well as ordinary data structures such as lists and trees. To achieve this goal, we use a categorical approach to initial algebra semantics in a presheaf category. That approach follows the line of Fiore, Plotkin and Turi's models of abstract syntax with variable binding.

Data decision diagrams for Promela systems analysis

In this paper, we show how to verify computation tree logic (CTL) properties, using symbolic methods, on systems described in Promela. Symbolic representation is based on data decision diagrams (DDDs) which are n-valued Shared Decision Trees designed to represent dynamic systems with integer domain variables. We describe principal components used for the verification of Promela systems (DDD, representation of Promela programs with DDD, the transposition of the execution of Promela instructions into DDD). Then we compare and contrast our method with the model checker SPIN or classical binary decision diagram (BDD) techniques to highlight as to which system classes SPIN or our tool is more relevant.

Towards the Development of Speaker-Dependent and Speaker-Independent Hidden Markov Model-Based Thai Speech Synthesis

Problem statement: Tone distortion in Thai languages can deteriorate not only the intelligibility of speech but also its naturalness. Therefore, the correctness of tone must be carefully taken into account in continuous speech synthesis. The preliminary work confronted this problem when applying HMM-based speech synthesis to Thai. Approach: This study presented a study on speaker-dependent and speaker-independent Hidden Markov Model (HMM)-based Thai speech synthesis. In the speaker-dependent system, we developed a simple tone-separated tree structure in the tree-based context clustering process of the training stage to treat the tone distortion problem. In the speaker-independent system or averaged-voice-model system, a number of tonal features are extracted and applied with the Speaker Adaptive Training (SAT) and Shared Decision Tree (STC) techniques to release the tone distortion problem. Results: Our objective evaluation revealed that the proposed features could make the F0 contour closer to the target speaker’s real contour. The results from our subjective test also revealed that the proposed tonal features could improve the tone intelligibility of all speech-model scenarios of male and female. Conclusion: By applying our approach, the problem of tone distortion can be relieved effectively. The better tone correctness can improve the intelligibility and the naturalness of speech significantly.

Tabu search algorithm for RP selection in PIM-SM multicast routing

With the development of network multimedia technology, more and more real-time multimedia applications need to transmit information using multicast. To construct a multicast tree is the basis of multicast data transmission. The prime problem concerning the construction of a shared multicast tree is to determine the position of the root of the shared tree, which is a center selection problem. The selection of the center Rendezvous Point (RP) directly affects the structure of the tree, and the performance of multicast accordingly. This paper proposes a multicast RP selection algorithm based on tabu search in PIM-SM multicast routing. This algorithm selects RP by considering both cost and delay. Simulation results show that good performance is achieved in multicast cost, end-to-end delay and register delay.

Heuristic algorithms for designing self-repairing protection trees in mesh networks

Protection trees have been used in the past for restoring multicast and unicast traffic in networks in various failure scenarios. In this paper we focus on shared self-repairing trees for link protection in unicast mesh networks. Shared protection trees have been proposed as a relatively simple approach that is easy to reconfigure and could provide sub-second restoration times with sub-optimal redundancy requirement. The self-repairing nature of this class of protection trees may make them an attractive option for cases where dynamic changes in network topology or demand may occur. In this paper, we present heuristic algorithms to design a self-repairing protection tree for a given network. We study the restorability performance of shared trees and examine the limitations of such schemes in specific topologies, such as cases where long node chains exist. Using extensive simulations with thousands of randomly generated network graphs. We compare redundancy and average backup path length of shared protection trees with optimal tree designs and non-tree designs. We also apply our algorithms to the problem of designing the protection tree in a pre-designed fixed-capacity network, and study the performance of shared protection trees in this scenario under different network loads and link utilization levels.

Arranging multicast forwarding table in class sequence in ternary-cam for line-speed lookup

PIM-SM (Protocol Independent Multicast-Sparse Mode) is a main multicast routing protocol in the IPv6 (Internet Protocol version 6). It can use either a shared tree or a shortest path tree to deliver data packets, consequently the multicast IP lookup engine requires, in some cases, two searches to get a correct lookup result according to its multicast forwarding rule, and it may result in a new requirement of doubling the lookup speed of the lookup engine. The ordinary method to satisfy this requirement in TCAM (Ternary Content Addressable Memory) based lookup engines is to exploit parallelism among multiple TCAMs. However, traditional parallel methods always induce more resources and higher design difficulty. We propose in this paper a novel approach to solve this problem. By arranging multicast forwarding table in class sequence in TCAM and making full use of the intrinsic characteristic of the TCAM, our approach can get the right lookup result with just one search and a single TCAM, while keeping the hardware of lookup engine unchanged. Experimental results have shown that the approach make it possible to satisfy forwarding IPv6 multicast packets at the full link rate of 20 Gb/s with just one TCAM with the current TCAM chip.

A genetic algorithm for solving virtual source placement problem on WDM networks

As WDM technology matures and multicast applications become increasingly popular, supporting multicast at the WDM layer becomes an important and yet challenging topic. In order to reduce the number of wavelength channels to achieve the multicast effectively, switching nodes with light-splitting and wavelength-converting capabilities denoted as virtual source ( VS) nodes are developed. In this paper, given a WDM network, a positive integer k and a set of multicast requests, the VS placement (VSP) problem on WDM networks is studied; the goal is to determine the locations of the VS nodes, the multicast routing and assigned wavelengths of multicast requests so as to minimize the number of used wavelength channels. Since the VSP problem is a hard problem, a genetic algorithm (GA) is proposed to solve it. In the proposed GA, a binary-bit array is used to represent the locations of the VS nodes on network. For a given locations of VS nodes, three multicast routing methods: core-based tree (CBT), link-disjoint CBT (LDCBT), and layered graph (LG) are proposed and used to construct the shared tree for multicast requests. In the CBT and LDCBT methods, a multicast tree constructing (MTC) algorithm is used to construct the multicast tree of a given multicast, and a segment-based wavelength assignment (SBWA) algorithm is proposed and used to determine the assigned wavelength of the multicast tree. Moreover, in the proposed GA, several crossover and mutation operators are developed and used to generate offspring. Simulation results show that the proposed GA together with LG or CBT multicast method can get better results.

Between underlay and overlay

PurposeThis paper aims to discuss problems, requirements and current trends for deploying group communication in real‐world scenarios from an integrated perspective.Design/methodology/approachThe Hybrid Shared Tree is introduced – a new architecture and routing approach to combine network – and subnetwork‐layer multicast services in end‐system domains with transparent, structured overlays on the inter‐domain level.FindingsThe paper finds that The Hybrid Shared Tree solution is highly scalable and robust and offers provider‐oriented features to stimulate deployment.Originality/valueA straightforward perspective is indicated in the paper for a mobility‐agnostic routing layer for future use.

Multicast traffic aggregation in MPLS-based VPN networks

This article gives an overview of the current practical approaches under study for a scalable implementation of multicast in layer 2 and 3 VPNs over an IP-MPLS multiservice network. These proposals are based on a well-known technique: the aggregation of traffic into shared trees to manage the forwarding state vs. bandwidth saving trade-off. This sort of traffic engineering mechanism requires methods to estimate the resources needed to set up a multicast shared tree for a set of VPNs. The methodology proposed in this article consists of studying the effect of aggregation obtained by random shared tree allocation on a reference model of a representative network scenario.