As the Internet is expected to better support multimedia applications, new services need to be deployed. One of them is the group communication service for one-tomany or many-to-many data delivery. After more than a decade of important research and development efforts, the deployment of multicast routing in the Internet is far behind expectations. Therefore, a first motivation for an alternative group communication service is to bypass the lack of native IP multicast routing. Although less efficient and scalable than native multicast routing, such alternative services are suitable for the purpose. A second possible motivation is to go beyond the limitations of classic multicast routing for very specific working environments. In this article we identify, classify, and discuss some of these alternative approaches. Agroup communication service refers to the ability to send information to several receivers at the same time, using either a one-to-many or many-tomany model. The any-source and source-specific

Scalability of multicast forwarding state is likely to be a major issue facing inter-domain multicast deployment. In this paper, we present a comprehensive analysis of the multicast forwarding state problem. Our goal is to understand the scaling trends of multicast forwarding state in the Internet, and to explore the intuitions that have motivated state reduction research. We conducted simulation experiments on both real and generated network topologies, with a range of parameters driven by multicast application characteristics. We found that the increase in peering among Internet backbone networks has led to more multicast forwarding state at a handful of core domains, but less state in the rest of the domains. We observed that scalability of multicast forwarding state with respect to session size follows a power law. Our findings show that distribution and concentration of multicast forwarding state in the Internet is significantly impacted by application characteristics. We investig...

This paper focuses on understanding the scale and the distribution of “state overhead ” (briefly load) that is incurred on the routers by various value-added network services, e.g., IP multicast and IP traceback. This understanding is essential to developing appropriate mechanisms and provisioning resources so that the Internet can support such value-added services in an efficient and scalable manner. We mainly consider the number of end-to-end paths or trees intersecting at a router to represent the amount of state overhead at that router. Hence, we analyze the router-level intersection characteristics of end-to-end Internet paths or trees to approximate the state overhead distribution in the Internet. For the reliability of our analysis, a representative, end-to-end router-level Internet map is essential. Although several maps are available, they are at best insufficient for our analysis. Therefore, in the first part of our work, we exert a measurement study to obtain a large size end-to-end router-level map conforming to our constraints. In the second part, we conduct various experiments using our map and shed some light on the scale and distribution of state overhead of value-added Internet services in both unicast and multicast environments. 1

support is essential to facilitate multi-sender multimedia multicast applications such as video conferencing and virtual collaboration applications. In this paper, we introduce a new distributed core selection protocol that has the following desirable properties. First, the protocol utilizes a new distributed primary core selection algorithm that selects as many primary cores per multicast group as necessary to maximize the number of group members with satisfied QoS requirements. Second, the protocol is distributed, preventing a single router from becoming a hot spot and a single point of failure during core selection. Last, the protocol employs a distributed backup core selection algorithm to provide quick recovery should some primary cores fail. Our analytical experiments show that the proposed protocol significantly satisfies more group members with noticeably less communication overhead than a recent core selection algorithm with QoS support using a single core. Index Terms — Quality of Service, Multicast, Core-based Routing I.

Core-based routing with Quality of Service (QoS) support is essential to facilitate multi-sender multimedia multicast applications such as video conferencing and virtual collaboration applications. In this paper, we introduce (i) a new application-level service class framework that allows group members to indicate their desired service quality easily; (ii) two new core selection protocols that utilize a new primary core selection algorithm to select as many primary cores per multicast group as necessary to maximize the number of group members with satisfied QoS requirements; and (iii) backup core selection algorithms that select good backup cores to enable quick recovery should some primary cores fail. Our analytical experiments show that the proposed protocols significantly satisfy more group members with noticeably less communication overhead than a recent core selection algorithm with QoS support using a single core.

Abstract — IPv6 is intended to be the next network layer protocol of the Internet and it is designed to overcome the limitations of the current IPv4 protocol. However, the lack of resources in routers will still be an issue with the deployment of state storing protocols in the IPv6 network. In particular, multicast protocols will most probably take over resources up to their limits for maintaining multicast tree information. The aim of this paper is to study the possible benefit of distributing the multicast tree states on the IPv6 topology in order to optimize the IPv6 network resource usage. To be able to carry out this study we first had to map the topology of the current IPv6 network. We have used our network cartographer software in order to build an accurate map of the IPv6 network. We have then studied the distribution of multicast states by using a simple repartition function. We have found that the use of this function can heavily decrease the number of states stored by the most loaded nodes at the cost of a small overall increase of the total number of states on the topology. I.

Overlay hosting systems such as PlanetLab, and cloud computing environments such as Amazon’s EC2, provide shared infrastructures within which new applications can be developed and deployed on a global scale. This paper explores how systems of this sort can be used to enable advanced network services and sophisticated applications that use those services to enhance performance and provide a high quality user experience. Specifically, we investigate how advanced overlay hosting environments can be used to provide network services that enable scalable virtual world applications and other large-scale distributed applications requiring consistent, real-time performance. We propose a novel network architecture called Forest built around persession tree-structured communication channels that we call comtrees. Comtrees are provisioned and support both unicast and multicast packet delivery. The multicast mechanism is designed to be highly scalable and lightweight enough to support the rapid changes to multicast subscriptions needed for efficient support of state updates within virtual worlds. We evaluate performance using a combination of analysis and experimental measurement of a partial system prototype that supports fully functional distributed game sessions. Our results provide the data needed to enable accurate projections of performance for a variety of session and system configurations.

During the last two decades, several value-added services (e.g., IP multicast, IP traceback, etc.) have been proposed to extend the functional capabilities of the Internet. Due to the increasing role of these services, there is a need to better understand their impact on the network. In this paper, we present an experimental study on the intersection characteristics of end-to-end Internet paths and trees. We analyze these characteristics to understand the scale and the distribution of “state overhead ” that is incurred on the routers by various value-added network services. For the reliability of our analysis, a representative, end-to-end router-level Internet map is essential. Although several maps are available, they are at best insufficient for our analysis. Therefore, in the first part of our work, we exert a measurement study and present an alternative approach to obtain an end-to-end router-level map conforming to our constraints. In the second part, we conduct various experiments using our map and shed some light on the scale and distribution of the state overhead of value-added Internet services in both unicast and multicast environments.

Core-based routing with Quality of Service (QoS) support is essential to facilitate multi-sender multimedia multicast applications such as video conferencing and virtual collaboration applications. In this paper, we introduce a new distributed core selection protocol that has the following desirable properties. First, the protocol utilizes a new distributed primary core selection algorithm that selects as many primary cores per multicast group as necessary to maximize the number of group members with satisfied QoS requirements. Second, the protocol is distributed, preventing a single router from becoming a hot spot and a single point of failure during core selection. Last, the protocol employs a distributed backup core selection algorithm to provide quick recovery should some primary cores fail. Our analytical experiments show that the proposed protocol significantly satisfies more group members with noticeably less communication overhead than a recent core selection algorithm with QoS support using a single core.