To multicast a live stream, you would need to setup
Push Publishing on your Streaming Engine.
Here's the description on this module:
Push Publishing technology in Wowza Streaming Engine software is a module and API that enables push publishing of live streams by using Real Time Messaging Protocol (RTMP), Apple HLS (cupertino), Adobe HDS (sanjose), MPEG-2 Transport Stream (MPEG-TS), and Real Time Transport Protocol (RTP). Live streams can be published to destinations such as Content Delivery Networks (CDNs) for re-streaming, Adobe Media Servers, other media servers running Streaming Engine software, or multicast networks.