Abstract
Network operators have been reluctant to deploy IP multicast services mainly due to the lack of native control rover multicast groups. This lack of control does not only prevent operators from generating revenue from multicast-based services but also hinders regular network management. In this work we identified the network elements where admission control should be enforced for multicast session spawning over heterogeneous access networks. The architecture proposed uses existing AAA functionality to perform user identification and multicast session admission control. This control is made at the network layer with no protocol modifications. Three access networks were considered: xDSL, WiMAX and UMTS.

Abstract
Technological evolution is leading telecommunications toward all-IP scenarios, where multiple services are transported as IP packets. Among these services is the broadcast of video. A possible mechanism for broadcasting multiple video channels over IP is to use IP multicast, and let each client decide about the reception of a channel. The secure IP multicast specified by the IETF MSEC working group is a candidate solution for securing these broadcast services. In this paper we propose a new solution for supporting the broadcast of multiple video channels which can be accessed only by authorized users; besides, when a video channel is not visualized in the last mile its transmission is temporarily suspended, so that the cable can be used for other services such as standard Internet access.

Abstract
Technological evolution is leading telecommunications to all-IP networks where multiple services are transported as IP packets. Among these are the group communications services with confidentiality requirements. Secure IP multicast may be used to secure the broadcast of video channels. However, in scenarios such as cable TV where the concept of video channel and bundle are present, groups are very large, and users switch very rapidly between channels (zapping), a sort of problems still need to be addressed. The solution proposed in this paper addresses these problems. For that purpose, a centralized form of secure group communications is proposed also used to transmit, not data, but group cryptographic material. Threes types of cryptographic keys are used. End systems use this material to decrypt the data sent by the content providers.

Abstract
IPTV services consist of multiple video channels grouped in bundles, such as sports, movies or generic bundles; users typically subscribe multiple bundles, including the generic bundle. Secure IP multicast can be used to implement IPTV services, but it still has problems to be addressed. Current solutions require high computational power in video channel zapping situations, lack support for groups sourced at the users, and present a weak support for admission control in IP multicast for both sources and receivers in dynamically configured environments. This work proposes a new, secure and efficient IPTV solution that, cumulatively: (a) enforces individual access control to groups of real-time IPTV video channels; (b) enforces IP multicast admission control for both multicast senders and receivers; (c) supports user generated videos; (d) generates low signaling overheads; (e) does not introduce perceivable delays, particularly in video channel zapping situations. Moreover, this solution can be easily integrated in the IPTV architectures being developed by ETSI and ITU-T.

Abstract
The Internet is characterized by the coexistence of two Internet Protocol (IP) versions and multiple autoconfiguration mechanisms which are deployed targeting specific communication scenarios. This heterogeneity requires user pre-configurations, namely with respect to the proper autoconfiguration mechanism to be used at each time. On the other hand, future networks may imply that users own personal networks demanding self-configuration and self-management, and being part of very dynamic scenarios. In this paper we make a survey of the autoconfiguration mechanisms available for IP networks, and argue that a new solution is needed, so that the proper autoconfiguration mechanism can be selected automatically, dynamically and efficiently, and future communication paradigms can be properly addressed. Copyright 2005 ACM.

Abstract
The test and performance evaluation of high speed networks pose problems that cannot be solved by traditional equipment. In this paper, the concept of a powerful and versatile tool, capable of generating and detecting traffic to test and assess the performance of such networks, is presented.