Uma avaliação dos mecanismos de trasmissão de tráfego para IPTV

Abstract

The IPTV service offer is currently the main interest of many ISPs (Internet Service Providers). Such service comprises the continuous transmission, via an IP network, of TV programs structured into channels, like the open TV ou cable TV services. The goal is to reach the same quality of conventional TV (full screen, medium or high definition), adding the interactivity of the Internet. Among the challenges, there is the need of optimizing the video traffic distribution in the IP network, given its heavy bandwidth demand. Finding which is the best distribution technology for this purpose, in a corporative network, was the main objective of the present work. A network was implemented with the ns-2 network simulator, using real world topology and traffic from an ISP. Simulations used different video traffic traces, characterizing an IPTV scenario. To identify the traffic distribution mechanism that imposed less bandwidth burden during IPTV transmission, the work tested different approaches using unicast and multicast (with PIM-DM, PIM-SM, and PIM-SSM). Additionally, the zapping (channel change time) performance of each multicast approach was evaluated. The best result was achieved by the PIM-SSM (Protocol Independent Multicast - Source-Specific Multicast), which imposed a reduced load in the network and produced the smaller zapping time (0.2 s). As no P2P (Peer to Peer) implementation was available for the ns-2, this mechanism could not be simulated. However, a teoretical study showed that multicast is superior to P2P, for an IPTV scenario. The results suggested that, using proper traffic distribution mechanisms, the implementation of IPTV services on current corporative IP networks is feasible, in spite of the required bandwidth.