## 1 Introduction  
Even though the Internet has brought many new entertainment opportunities, watching television remains as one of the primary leisure activities around the world (average TV watching time per person is 24 hours per week in North America [1]). Internet Protocol TV (IPTV) has given new dimensions to the television experience with advanced features such as interactivity, personalization and localization [2] that conventional TV broadcasting is unable to support. Also, the deployments of equipment (for network operators), services (for service providers) and contents (for content producers) have become increasingly simplified in an IP environment. ITU-T [3] and ETSI-TISPAN [4] are working towards architectural frameworks and IETF is continuously engineering the TCP/IP protocols suitable also for video communications. IPTV is currently deployed in walled-garden networks using multicast to deliver live (linear) TV channels whereas Video on Demand (VoD) uses unicast, which delivers pre-recorded programs to the IPTV users in the same networks. Numbers of IPTV subscribers and bandwidth requirements of the contents with High-Definition (HD) and 3-Dimensional (3D) video are increasing day by day at a higher rate than the technologies for network bandwidths are improved. As a result over-provisioned walled-garden IPTV networks may become congested in the recent future. In another way some parts of the public Internet will be multicast capable to deliver IPTV subjected to the challenge of Quality of Service (QoS) guarantee. QoS provisioning in the future Internet is not about commissioning hardware resources endlessly. Therefore we need to address this issue by optimally managing the network resources. In IP multicast (also called native multicast), a single packet from the source is delivered to multiple receivers where multicast enabled routers duplicate packets as needed (creating a tree). This reduces traffic in the network when simultaneously communicating to a group of users. IP multicast standards have evolved by the IETF since 1989 when it was first introduced by [PERSON] [5]. Due to deployment issues like scalability, congestion control, reliability and security, it has not been made available end-to-end over the public Internet but has been deployed in research networks like Internet2 MBone [6] and by some ISPs like JANET. After a long time in research, development and standardisation, IPTV today has grasped the advantages of multicast. A multicast session is uniquely identified by a multicast address and routing is based on this multicast address in the destination address field (_i.e._, in contrast to the destination network-prefix based routing in unicast). As a result, each multicast router should maintain the multicast addresses of all the sessions that are flowing through it. We propose to exploit the routers' session information in a controlled way so that an end-user can discover other multicast sessions in its network proximity and reduce network traffic by joining with them. This paper analyses in detail the requirements for using this in-network capability of multicast to discover proximate sessions and develops a new socio-economic service paradigm for the benefit of end-users and IPTV providers. This novel system called _ProxyTV_ generates incentives to encourage users to join an existing multicast session (_i.e._, a linear TV channel), which is closer (in network proximity) to a user, rather than watching a new channel. This can drastically reduce traffic in IPTV networks and, in turn, provide enhanced Quality of Experience (QoE) for the end-user. Multicast service discovery using centralized servers where end-users explicitly inform about the sessions has been a research topic for a long time. However, it does not provide any information aboutgeographical proximity. [PERSON] _et al._[7] has proposed an approach to integrate geographical information into multicast service discovery without using more precise router information, which is related to our proposed concept.