Reconstruction Of Multicast Tree Research Articles

Recovery and Reconstruction of Multicast Tree in Software-Defined Network: High Speed and Low Cost

Multicast is an efficient tool to transfer the same data from a publisher to multiple subscribers, and its performance relies critically on the resiliency. Compared with traditional networks, the centralized control and flexible programmability of the Software Defined Network (SDN) is more beneficial for solving the failure recovery problem. This paper presents a design of an OpenFlow controller which can recover and reconstruct a multicast tree rapidly, while reducing the Ternary Content Addressable Memory (TCAM) consumption simultaneously. We choose the protection mechanism, and calculate all the backup paths after the topology information is mastered by the controller. When a failure occurs, affected switches can enable the use of backup paths to continue forwarding multicast packets. As duplicate packets may exist after the failure recovery, the reconstruction of a tree is required by modifying only a small fraction of forwarding rules. The performance evaluations demonstrate that our proposed method recovers a multicast tree with a high speed and low cost. On one hand, the maximum failure recovery time of two protection-based methods including our proposed method is less than 11 ms, while that of two restoration-based methods is 44 ms and 30 ms, respectively. On the other hand, the amount of backup forwarding entries required by another protection-based method exceed our proposed method as long as 3 or more multicast groups exist in the network. Moreover, when our proposed method is adopted, the amount of backup forwarding entries per switch is less than 30, which can be ignored when compared with the capacity of SDN switches (a switch can support a few thousand forwarding rules).

A distributed time-limited multicast algorithm for VANETs using incremental power strategy

Efficient information dissemination is the pinnacle of Vehicular Ad-hoc Networks (VANETs). In case of delay-sensitive information such as safety-related messages, it is imperative to minimize the transmission delay and increase the message reliability in VANETs. In a previous work, we proposed a Time-Limited Reliable Broadcast Incremental Power (TRBIP) algorithm, which is a centralized heuristic to reduce transmission interferences for safety message dissemination in VANETs. By reducing the total transmission energy and the number of hops, TRBIP is able to reduce the transmission interference and thus-forth maximizes the reliability. Furthermore, in TRBIP, VANETs’ features such as vehicle mobility and frequent network fragmentation are also taken into account through store-carry-and-forward and the periodic multicast tree reconstruction strategies. However, multicast tree management is hard to maintain in urban environments due to the high density of nodes in VANETs (large trees), and is affected by the city streets organizations (intersections, roundabout, ... etc.). To address the afore-mentioned issues, in this paper we propose a Distributed version of Time-Limited Reliable Broadcast Incremental Power (DTRBIP) based on a road segmentation technique. Our proposal is extended to handle both delay-sensitive and delay-tolerant applications, and also both low and high dynamic VANETs scenarios respectively urban and highway environments. The results of the simulation conducted using NS-2 simulator advocate for the efficiency of our proposed method in term of reducing the total emission energy (at least by 150 dBm), reducing the average delay by 52%, increasing the packet delivery ratio by more than to 5%, and reducing the protocol overhead up to 3%. Obtained results show a clear enhancement compared to the previous solutions (i.e, RGRP-SA, RBIP, and TRBIP).

Improving Fault Resilience and Reconstruction of Overlay Multicast Tree Using Leaving Time of Participants

Improving Fault Resilience and Reconstruction of Overlay Multicast Tree Using Leaving Time of Participants

An Active Multicasting Mechanism for Mobile Hosts in Wireless Networking Environments

To support mobile multicasting in wireless networks, we present a new active multicasting mechanism which makes use of the state characteristic of multicast agent. In this mechanism, a multicast agent just locates the position for roaming hosts when it does not forward multicast packets. Upon reception of multicast packets, the multicast agent adjusts the service range to achieve an appropriate balance between routing efficiency and the overhead of multicast tree reconstruction. Therefore, a lot of unnecessary tree reconstructions are eliminated during the time when none multicast packet is transferred and multicast delivery path is near optimal because of the limited service range of multicast agent in the active state. To justify the effectiveness of our proposed scheme, we develop an analytical model to evaluate the signaling overhead. Our performance analysis shows that the proposed scheme can significantly reduce the system overhead and multicast routing is near optimal. The other important contribution is the novel analytical approach in evaluating the performance of mobile multicast routing protocol.

A Distributed Overlay Multicast Tree Reconstruction Algorithm for Live Streaming Media Applications

Recently overlay multicast has become one of the hot issues on multicast research, as it is more flexible than IP multicast and can facilitate application-specific optimization. However, the intermediate nodes in overlay multicast are easier to be faulted compared to those in IP multicast. So it is significant to design an efficient topology maintenance algorithm in overlay multicast, especially for the live streaming media applications. In this paper, the degree and delay constrained topology maintenance problem is studied, and a novel distributed multicast tree reconstruction algorithm called LOcal Topology maintenance Algorithm (LOTA) is proposed. By adopting the active strategy and avoiding package duplicates, LOTA triggers nodes pre-calculate a backup parent periodically before the multicast tree splits rather than letting downstream nodes find a new parent after a node's departure. When a node which is neither root nor leaf is gone, all its children can interact with their respective backup parents to restore the tree immediately in order to enhance the reconstruction performance and save the system maintenance cost effectively. The results of simulation and experiment show that, in both the small-scale and the large-scale group, LOTA's efficiency of tree reconstruction is much higher than the passive strategies, and its control overhead is comparatively low. Therefore, the algorithm is quite suitable for the real-time streaming media applications.

Overlay multicast tree recovery scheme using a proactive approach

Overlay multicast scheme has been regarded as an alternative to conventional IP multicast since it can support multicast functions without infrastructural level changes. However, multicast tree reconstruction procedure is required when a non-leaf node fails or leaves. In this paper, we propose a proactive approach to solve the aforementioned defect of overlay multicast scheme by using a resource reservation of some nodes’ out-degrees in the tree construction procedure. In our proposal, a proactive route maintenance approach makes it possible to shorten recovery time from parent node’s abrupt failure. The simulation results show that proposed approach takes less time than the existing works to reconstruct a similar tree and that it is a more effective way to deal with more nodes that have lost their parent nodes due to failure.

로컬 변환에 의한 오버레이 멀티캐스트 트리의 성능 최적화 기법

오버레이 멀티캐스트는 하드웨어적인 인프라 구축 없이도 시스템의 자원과 네트워크 대역폭을 효율적으로 사용할 수 있는 기법이며 중간 노드의 이탈이 발생하게 될 경우 멀티캐스트 트리를 재구성한다. 그러나 빈번한 멀티캐스트 트리의 재구성은 심각한 성능 저하를 가져오게 된다. 본 논문에서는 이러한 성능저하를 보완하기 위해 각 자식 노드들로부터 소스 노드에게 주기적으로 피드백 되어오는 정보(RTCP-probing)를 기반으로 트리 성능 최적화 알고리즘을 제안한다. 제안된 모델은 서비스하는 부모노드가 트리의 성능을 저하시키는 원인으로 판단되어질 때 수행하는 메커니즘이다. 메커니즘을 수행하여 성능 최적화 트리를 구성함으로써 전체적인 서비스 트리의 성능을 향상시켰다. 시뮬레이션 결과를 통해 제안된 모델뿐만이 아니라 기존의 기법들에 적용하였을 때도 효과적인 방안임을 보여주고 있다. Overlay Multicast is an effective method for efficient utilization of system resources and network bandwidth without a need for hardware customization. Multicast tree reconstruction is required when a non-leaf node leaves or fails. However frequent multicast tree reconstruction introduces serious degradation in performance. In this paper, we propose a tree performance optimization algorithm to solve this defect by using information(RTCP-probing) that becomes a periodic feedback to a source node from each child node. The proposed model is a mechanism performed when a parent node seems to cause deterioration in the tree performance. We have improved the performance of the whole service tree using the mechanism and hence composing an optimization tree. The simulation results show that our proposal stands to be an effective method that can be applied to not only the proposed model but also to existing techniques.

Real-time multicast in wireless communications

This paper presents methods for the reconfiguration of a multicast tree at the instance of node migration in cellular wireless networks. We consider a novel, and highly practical, formulation of the real-time multicast problem. Unlike the traditional notion of source to leaf node message transmission time being the measure for real-time, we consider the multicast tree re-construction time (in the event of a node migration) as the measure for real-time constraints. The overall goal is to minimize both the delays: i) delay of re-constructing the multicast tree and ii) source to destination transmission delay. In this paper, we introduce and provide solutions for the first objective, while the current research in real-time multicast tree considers the latter objective only. We propose two heuristics to solve the real-time multicast tree re-construction problem, one as a foreground and the other as a background algorithm, and present analysis and simulation results for several factors that contribute differently to the re-construction delay.