Multicasting is a scalable solution for group communication. Whereas secure unicast is a wellunderstood problem, scalable secure multicast poses several unique security problems, namely group membership control, scalable key distribution to a dynamic group. We address scalability in the proposed protocol by using hierarchical subgrouping. Third party hosts or members of the multicast group, designated as subgroup members, are responsible for secret key distribution and group membership management at the subgroup level. Unlike existing secure multicast protocols, our protocol, through dual encryption, can use "untrusted" subgroup managers to distribute data encryption keys securely. We analytically prove the correctness of the protocol in ensuring secure communication, describe possible collusion scenarios and our protocol's ability to overcome them. We compare our protocol with existing scalable key distribution schemes through simulation using real-life multicast traces and show that ...

The use of proxies for local error recovery and congestion control is a scalable technique used to overcome a number of wellknown problems in Reliable Multicast (RM). The idea is that the multicast delivery tree is partitioned into subgroups that form a hierarchy rooted at the source, hence the term Hierarchical Reliable Multicast (HRM). For each subgroup, there is a designated node, the proxy, which is responsible for collecting the feedback from the subgroup and for locally re-transmitting the lost packets. The performance of any RM protocol is affected by the underlying multicast routing tree and its loss characteristics. Furthermore, the performance of the HRM approach, in particular, strongly depends on the appropriate partitioning of the tree and the selection of proxies. In this paper, we first model the HRM problem, then define and compute appropriate performance metrics and finally give insights on the optimal location of proxies. Keywords Performance analysis, reliable mult...

Reliable multicast protocols on top of the MBone are presently subject to intensive research. In the past, numerous protocols have been developed and their respective performance been analysed. Little progress has been made, though, to compare different approaches. In this paper, we use the network simulator ns-2 to evaluate the performance of three protocols, namely Scalable Reliable Multicast (SRM), Multicast File Transfer Protocol (MFTP) and an enhanced version of the latter, called Multicast File Transfer Protocol with Erasure Correction (MFTP/EC). We also compare the results to each other and test the suitability for multicast file distribution. Keywords: Reliable Multicast, Network Simulator, Scalability 1 Introduction Protocols for the reliable one-to-many data transfer can be constructed in various ways, and existing protocol architectures in fact use completely different techniques. As a consequence, they differ in bandwidth consumption and quality of service they offer to t...

Most of the existing reliable multicast transport (RMT) protocol techniques that are suited for satellite networks adopt various design techniques that may limit or enhance their scalability to large receiver groups in one-to-many topologies. Satellite networks (with high bandwidth capacity and multi-spot beam support at the Extra High Frequency (EHF) spectrum), may provide a complementary solution to scalability although at a cost. Prolonged link fades due to varying weather patterns predominantly cause packet loss and unnecessary retransmission (form source or receiver) when link is unavailable. Analysis of RMT reliability techniques over links with persistent fade, shows that hybrid Forward Error Correction (FEC) with Automatic Repeat Request (ARQ) show better performance and efficiency in terms of robustness, goodput and redundancy.

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Existing solutions for streaming multimedia in the Internet do not scale in terms of object size and number of supported streams. Using separate unicast streams, for example, will overload both network and servers. While caching is the standard technique for improving scalability, existing caching schemes do not support streaming media well. In this paper, we propose a complete solution for caching multimedia streams in the Internet by extending existing techniques and proposing new techniques to support streaming media. These include segmentation of streaming objects, dynamic caching, and self-organizing cooperative caching. We consider these techniques in an integrated fashion. We implemented a complete caching architecture called SOCCER using the network simulator ns-2 and evaluate the effectiveness of each proposed technique and compare them to alternative caching solutions.