PaCRA: A Path-aware Content Replication Approach to support QoS guaranteed video on demand service in metropolitan IPTV networks

The recent years have seen an explosive upsurge in the popularity of IPTV networks and the IPTV user base. The increased user base poses new challenges to ISP in providing the IPTV services with the expected QoE to the users due to the increase in traffic and heterogeneity in networks. The VoD, being the most prominent and most lucrative of the triple play components, require efficient managing in order for the ISP to meet the expectations of the users, ie. efficient management of contents. The existing content management techniques that have been applied in CDN and P2P networks are not applicable to the VoD system in IPTV due to the difference in network characteristics. The available IPTV content management techniques can only provide sub-optimal performance as they do not take into account the load on the links. In this paper, we propose a new IPTV architecture that supports coordinated route planning and content management using overlays. We present a new distributed content management approach namely PaCRA which intelligently performs content management by taking into account the server storage status, network path status and the content utility. We present experimental evaluations that show that PaCRA performs significantly better than the other standard approaches. We further show that the traditionally used Zipf distribution fails to provide an approximation for content popularity distribution and propose a new content popularity distribution which is found to closely follow the actual video popularity distribution.