Multicast Backbone

Multicast Backbone

Not every part of the internet is multicast-enabled. Multicast is only enabled in “islands”, either over the air with satellite/terrestrial TV/cellular broadcast, or over cables in certain network pockets. As ISPs don’t peer multicast, there is no way to access these services from the outside. Blockcast solves this problem by enabling the community to operate RELAY infrastructure that grows the coverage of multicast, bridging them into new islands where multicast is enabled.

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Blockcast RELAY node operators assist their ISP by acquiring streams from multicast sources that can't be reached from within the ISP, using an over-the-air antenna, or tunneling it over unicast using Automatic Multicast Tunnels (AMT, RFC 7450). RELAYs improve delivery efficiency, reducing the backhaul utilization of their ISPs, and improve quality to end-users. This relay architecture is a core component of the TreeDN (RFC 9706) design, where AMT relays — deployed as hardware (Juniper MX routers) or software (Linux kernel containers) — bridge multicast traffic to unicast-only networks, with automatic nearest-relay selection via DRIAD (RFC 8777).

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