White Paper Abstract:
Transit service providers have a challenge in an Internet where many local service providers are not multicast-enabled. How do they entice content owners to transmit video and other multicast traffic across their backbones? The cost model for the content owners may be prohibitively high if they have to pay for unicast streams for the majority of their subscribers. Until more local providers are multicast-enabled, there is a transition strategy proposed by the IETF and implemented in Juniper Networks® Junos® operating system called Automatic IP Multicast Without Explicit Tunnels (AMT). The configuration involves setting up relays at peering points in multicast networks that can be reached from gateways installed on hosts connected to unicast networks.
With AMT, multicast control messages are encapsulated in UDP and sent to relays, which then transmit them natively toward the source. This results in moving the replication point closer to the user, and cuts down on traffic across the transit provider’s network. Thus, the content owner can more easily see a profitable business model by avoiding the linear costs of adding unicast subscribers. AMT fosters the deployment of native IP multicast by enabling a potentially large number of nodes to connect to a multicast provider network that is already present. AMT is an interim solution to help build scalable video and other multicast services during the transition to multicast-enabled local service providers. All Juniper Networks M Series Multiservice Edge Routers, MX Series 3D Universal Edge Routers, and T Series Core Routers support AMT.