Overlay Multicast Network Research Articles

A Routing Algorithm in Heterogeneous Overlay Multicast Networks

Due to the difficulties in deployment of IP multicast, the overlay multicast networks (OMN) are being increasingly recognized as a viable alternative to construct a general multicast service infrastructure. To settle the heterogeneity of bandwidth required by real-time multimedia application, the multicast routing problem in heterogeneous OMN is discussed. A new network model of heterogeneous OMN is described by extending the degree-constrained model. Adopting the strategy of layered bandwidth allocation, a heuristic routing algorithm, called layered compact tree (LCT) is proposed to build a minimum delay radius multicast tree in heterogeneous OMN. The properties of LCT are also proved and analyzed in theory. The simulation results show that LCT could reduce both hops and network resource usage of the tree effectively, and keep a little increase in delay radius while the allocated bandwidth decreases.

Multicast tree rearrangement to recover node failures in overlay multicast networks

Overlay multicast makes use of the Internet as a low level infrastructure to provide multicast service to end hosts. The strategy of overlay multicast slides over most of the basic deployment issues associated with IP multicast, such as end-to-end reliability, flow and congestion control, and assignment of an unique address for each multicasting group. Since each multicast member is responsible for forwarding multicast packets, overlay multicast protocols suffer from multicast node failures. To cope with node failures in the overlay multicast networks, the employment of multicast service nodes (MSNs) is considered which allows relatively high processing performance to cover the disconnected nodes. We are interested in minimizing the cost of both the MSNs and additional links when a node failure occurs. Overlay multicast tree rearrangement to connect multicast members is discussed and formulated as a binary integer programming problem. The tree rearrangement problem is solved by a heuristic based on the Lagrangian relaxation. The performance of the proposed algorithm is investigated by carrying out experiments in 50 and 100 node problems. The employment of MSNs is illustrated to be dependent on the end-to-end delay bound in overlay networks and the degree constraint of member nodes.

Path-aware overlay multicast

We investigate a heuristic application-level (overlay) multicast approach, which we refer to as Topology Aware Grouping (TAG). TAG exploits underlying network topology data to construct overlay multicast networks. Specifically, TAG uses the overlap among routes from the source to group members to construct an efficient overlay network in a distributed, low-overhead manner. We can easily integrate TAG with delay and bandwidth bounds to construct overlays that satisfy application requirements. We study the properties of TAG, and quantify its economies of scale factor, compared to unicast and IP multicast. In addition, we compare TAG with delay-first and bandwidth-first Narada/End System Multicast (ESM) in a variety of simulation configurations. We also implement and experiment with TAG on the PlanetLab wide-area platform. Our results demonstrate the effectiveness of our heuristic in reducing delays and duplicate packets, especially when underlying routes are of high quality.

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.

Challenges and opportunities of delivering IP-based residential television services

This article describes the main challenges of implementing an end-to-end architecture for delivery of high-quality, IP-based residential TV services to residential customers. The IP-based approach can be implemented with an IP multicast overlay network with traditional routers or use IP-multicast-aware ATM switching systems. Both approaches use IP multicast to transport MPEG-2 broadcast video and can work on any access architecture, especially on copper-based architectures (xDSL) such as ASDL and VDSL. The main challenges met while implementing the IP-based architecture are competitive positioning relative to traditional CATV architectures, overall architecture, head-end architecture and quality issues, traffic engineering for stringent QoS requirements, IP multicast requirements, and business case considerations. The IP-based approach described leverages Internet technology advancements and capitalizes on the impacts of Internet on interactive entertainment. Video channel manipulation at the head-end is dependent on access bandwidth and affects video quality. Video traffic management to meet stringent QoS requirements is challenging at the IP layer. High-capacity, responsive IP multicasting is essential to achieving high service quality. Cost-effective IP multicasting is a critical component of the business case.