Today I explore multicast, where packets are delivered multiple times using a reverse routing table. Inspired by Tall Paul Tech, I demonstrate live TV distribution as a practical example of multicast on a home network.

Using FFmpeg, I stream a test file (Big Buck Bunny) both raw and transcoded into MPEG‑TS over UDP to the link‑local group ff02::69. For national broadcaster YLE in Finland, I pipe `yle-dl` output directly into FFmpeg to push channel TV1 to ff02::69 on port 5003. The examples assume MLD/IGMP snooping; otherwise wireless clients may suffer.

For multi‑subnet setups I use source‑specific multicast with FRR (Free Range Routing). The config enables IPv6 PIM on upstream/downstream interfaces, MLDv2, and an SSM prefix ff3e::/16. A routed stream uses the SSM address ff35::69 with a hop limit of 32. This shows how multicast can scale beyond a single LAN.