While the advantages of multicast delivery over multiple unicast deliveries is undeniable, the deployment of the IP multicast protocol has been limited to "islands" of network domains under single administrative control. Deployment of inter-domain multicast delivery has been slow due to both technical and administrative reasons. In this paper we propose a Host Multicast Tree Protocol (HMTP) that (1) automates the interconnection of IP-multicast enabled islands and (2) provides multicast delivery to end hosts where IP multicast is not available. With HMTP, end-hosts and proxy gateways of IP multicast-enabled islands can dynamically create shared multicast trees across different islands. Members of an HMTP multicast group self-organize into an efficient, scalable and robust multicast tree. The tree structure is adjusted periodically to accommodate changes in group membership and network topology. Simulation results show that the multicast tree has low cost, and data delivered over it experiences moderately low latency. I.

Multicast and anycast have received considerable attention due to their ability to support networked services. There are distinct and significant security vulnerabilities in both the multicast and anycast model including denial of service, theft of service, eavesdropping, and masquerading. The multicast problem requires a secure IGMP. The anycast problem requires secure anycast server advertisements. We generalize these two problems into a problem of group access control and propose Gothic, a complete architecture for providing group access control. Gothic centers around a novel authorization architecture. This is complemented by a proposal for a group policy management system that allows the group owner to be authenticated before being allowed to specify the group access rights. This system can be applied to other works that involve group policy. We show how Gothic operates in a number of environments including application-layer multicast, source-specific multicast, application-layer anycast and global IP-anycast. We evaluate the security and scalability of the architecture and show that it improves scalability over previous solutions while maintaining or increasing the level of security. We also propose methods of integrating Gothic with the group key management system and content distribution tree. We propose and evaluate a group access control aware group key management technique that leverages the existence of a group access control system to substantially reduce overhead.

The phenomenal growths of group communications and QoS-aware applications over the Internet have respectively accelerated the development of two key technologies, namely, multicasting and Differentiated Services (DiffServ). Although both are complementary technologies, the integration of the two technologies is a nontrivial task due to architectural conflicts between multicasting and DiffServ. In this paper, we propose an approach for providing multicast support across a DiffServ domain that is scalable in terms of group size, network size, and number of groups. We analyze our approach in a detailed manner for feasibility, adaptiveness, and deployment considerations.

Abstract Bandwidth in the Internet is constantly increasing. The last mile problem of the Internet has almost been solved. Multimedia has emerged as a dominant type of traffic on the Internet. Multicast is increasingly seen as the delivery vehicle of choice for multimedia streams. What has been the one true stumbling roadblock in widespread use of multicast is the lack of a convenient mechanism for multicast session discovery. This paper examines existing techniques that try to address this issue, highlighting the benefits and drawbacks of such schemes. It then proposes our hierarchical and globally scalable session directory architecture. An analysis of benefits and drawbacks of our scheme follows. The paper concludes with arguments why our scheme might be generally more suitable for global deployment, which may allow end users to enjoy the true power and efficiency of IP multicast.

The phenomenal growths of group communications and QoS-aware applications over the Internet have accelerated the development of two key technologies, namely, multicasting and Differentiated Services (DiffServ). Although both are complementary technologies, the integration of the two technologies is a non-trivial task due to architectural conflicts between multicasting and DiffServ. In this paper, we propose a protocol for member join/leave in a DiffServ network that is scalable in terms of group size, network size, and number of groups. We detail our join/leave protocol for both intra-domain and inter-domain routing as well as the various different types of multicast trees (single source tree, shortest path tree, shared tree, many-to-many tree). Finally, we present simulation studies regarding the performance of our join/leave protocol.

Building on the success of unicast IP, IP Multicast adopted a simple, open, best-effort delivery model with many-to-many semantics. Despite several years of effort, a general, scalable and reliable end-to-end transport protocol analogous to TCP has proven elusive. Proposed solutions are either inflexible, or incur high control overhead.

A new inter-client synchronization framework for one-to-many (i.e., multicast) media streaming is proposed employing a server-client coordinated adaptive playout control. The proposed adaptive player controls the playback speed of audio and video by adopting the time-scale modification of audio. Based on the overall synchronization status as well as the buffer occupancy level, the playout speed of each client is manipulated within a perceptually tolerable range. Additionally, the server implicitly helps increasing the time available for retransmission while the clients perform an interactive error recovery mechanism with the assistance of playout control. By coordinating the playout speed of each client, the inter-client synchronization with respect to the target presentation time is smoothly achieved. RTCP-compatible signalling between the server and group-clients is performed, where the exchange of controlling message is restricted. The network-simulator based simulations show that the proposed framework can reduce the playout discontinuity without degrading the media quality, and thus mitigate the client heterogeneity.

The significant growths of group communications and QoSaware applications over the Internet have accelerated the development of two key technologies, namely, multicasting and Differentiated Services (DiffServ). Although both are complementary technologies, their integration is a non-trivial task due to several architectural conflicts between them. The inherent heterogeneous nature of QoS multicasting further complicates this problem with the sender-driven nature of DiffServ. Thus, in this paper, we propose a method for providing heterogeneous QoS to multicast groups via dynamic DSCPs without per-group state information in the DiffServ core. We detail our approach as well as examine implications for an adaptive method for both multicast and unicast connections. Finally, we present simulation studies regarding the performance benefits of dynamic DSCPs in multicasting.

Despite a decade of research and development, multicast has not yet been deployed on a global scale. Among the difficulties with the current infrastructure are intermulticast fairness support, multicast congestion control, and multicast routing.

Multimedia group communication emerges to focal interest at mobile devices, enriching voice or video conferencing and complex collaborative environments. The Internet uniquely provides the bene t of scalable, dynamic group communication services, vitally aiding commonly limited mobile terminals. The traditional Internet approach of Any Source Multicast (ASM) routing, though, remains hesitant to spread beyond limited, controlled environments. It is widely believed that simpler and more selective mechanisms for group distribution in Source Speci c Multicast (SSM) will globally disseminate to many users of multicast infrastructure and services. Mobility management for the recent SSM standard is under debate SSM group session initiation up until now remains unsupported by the Session Initiation Protocol (SIP). In this paper we present straightforward extensions to SIP for negotiating SSM sessions. SIP protocol speci cations and semantic are compatibly extended without adding new SIP methods. We will introduce a multimedia communication software with distributed architecture as implementation reference. Furthermore mobility management of the underlying routing layer is discussed and evaluated on grounds of real-world Internet topologies. This ongoing work is supported by the German Bundesministerium