Implementations
Pay-TV operators and some educational institutions with significant on-campus student housing have deployed IP multicast to deliver one-way streaming media such as high-speed video to large groups of receivers. Additionally, there have been some uses of audio and video conferencing using multicast technologies. These are far less prevalent and are most often relegated to research and education institutions, which often have a greater degree of network capacity to handle the demands. Some technical conferences and meetings are transmitted using IP multicast. Until recently many of the sessions at the IETF meetings were delivered using multicast.
Another use of multicast within campus and commercial networks is for file distribution, particularly to deliver operating system images and updates to remote hosts. The key advantage of multicast boot images over unicasting boot images is significantly lower network bandwidth usage.
IP multicast has also seen deployment within the financial sector for applications such as stock tickers and hoot-n-holler systems.
While IP multicast has seen some success in each of these areas, multicast services are generally not available to the average end-user. There are two major, related, factors for this lack of widespread deployment. First, forwarding multicast traffic imposes a great deal of protocol complexity on network service providers. Second, core network infrastructure exposes a far greater attack surface, with particular vulnerability to denial-of-service attacks.
RFC 3170 (IP Multicast Applications: Challenges & Solutions) provides an overview of deployment issues.
Read more about this topic: IP Multicast