Multicast is an efficient mechanism to distribute content on IP networks. It hasn't lived up to its potential for a variety of reasons, perceived complexity among them, but the need is only growing. Growth in video over IP networks continues to explode, and even though much of this is on-demand (requiring unicast streaming), live, linear content is growing as well. Scaling backbones to support this is an expensive endeavor. Multicast represents a potential cost-effective solution.
Multicast is generally deployed in closed, private networks, with very little inter-provider capability. Automatic Multicast Tunneling (AMT) is a technology that allows users to bridge these island networks and access multicast content from unicast-only networks. AMT introduces two constructs: gateways and relays. The gateway receives requests to join multicast streams and can be bundled directly with an application, or run on a networking element. The relay is the function that joins the multicast stream, encapsulates it, and forwards it in a unicast tunnel to the gateway. Together, they can . . . do what?
CAAREN is partnering with Juniper Networks for this effort. We are running an AMT relay on a Juniper MX80. We are also sourcing several open-source videos.
If you would like to see how AMT works, you can download a development version of VLC, (what is VLC?) and follow the instructions to set the relay address. The README offers (samel?) AMT URLs you can join.
Another approach is to combine AMT with LISP - or is this just part of the above approach? We are combining AMT with Location-Identification Separation Protocol (LISP) to allow for streams to be sourced from anywhere on the Internet by providing a stable source IP address and the capability to source multicast from a unicast network. The LISP is a standard that decouples the two functions of IP address - where you are (your location on the network, used for routing) and who you are (host identification). This is very early work, but results are promising. More information about LISP can be found at lispers.net.