A distributed approach to multicast session discovery MDNS - A globally scalable multicast session directory architecture

This dissertation addresses the issue of multicast session discovery by an end user. IP Multicast has tremendous network bandwidth utilization benefits over conventional data transmission strategies. Use of multicast could prove cost effective for many Content Distribution Networks (CDN). From an end user perspective, accessing a live stream using multicast will result in better video reception quality compared to the unicast transmission. This being imposed largely due to limited line bandwidth being shared among several competing data streams. Still the deployment is very sparse in the Internet.;One of the reasons is less user demand due to lower usability compared to IP unicast. The supporting network infrastructure that was deployed after standardization of TCP protocol helped tremendously in improving the usability of IP unicast. The Domain Name Service (DNS) infrastructure allowed users to access target hosts using a Fully Qualified Domain Name (FQDN) string against using the dotted decimal IP addresses [1]. Since the unicast IP addresses were allotted in a regulated manner and because of the longevity of assignments, it became easier to search and locate resources on the Internet. Lack of such infrastructure support has deprived multicast its usability from an end user perspective. More importantly, shared nature of multicast addresses and the short life of address use and frequent reuse from the common pool makes it difficult to search and discover content by the end user.;This dissertation provides a distributed hierarchical architecture that efficiently addresses some of the usability issues raised above. The tree hierarchy closely co-located with the DNS infrastructure allows the presented scheme to assign Universal Resource Identifiers (URIs) for multicast streams that an end user can bookmark. The proposed scheme automatically re-maps the correct session parameters with the URIs in case they change in future. The Distributed Hash Table (DHT) approach for search and discovery of multicast sessions presented in this dissertation uses a tree hierarchy which is more suitable for the task at hand. Many live multicast streams are not replicated, so there is a need to locate the source of the data and therefore the search scheme required is somewhat traditional in nature. The relative instability of many multicast streams and associated session parameters makes many traditional P2P DHT schemes unsuitable for the problems addressed in this work.;Simulation results and analytical comparison of the proposed scheme with existing approaches are presented towards the end of this dissertation. A detailed discussion of why several of the existing DHT schemes for keyword search and Session Announcement Protocol (SAP) / Session Discovery Protocol (SDP) based multicast session discovery schemes are unsuitable for the identified problem is presented as well.