demo · v142

Multicast Packet Flow Visualizer

Watch packets propagate from a single sender to a multicast group of receivers simultaneously. Toggle individual receivers in and out of the group, then switch to unicast mode to see how many separate packets would be required instead — and what that does to bandwidth.

feature detection Checking for Direct Sockets API… The simulation runs in demo mode regardless — no real sockets are opened from this page.
mode
multicast
active receivers
4
packets sent
0

bandwidth comparison

multicast — 1 packet to group

1 packet/broadcast

unicast — N packets (one per receiver)

4 packets/broadcast

packet log

—waiting for first broadcast…

relevant API

// Chrome 142+: multicast UDP via Direct Sockets (Isolated Web Apps / origin trial)
const socket = new UDPSocket({
  remoteAddress: "239.0.0.1",   // multicast group address
  remotePort: 5000,
  dnsQueryType: "ipv4",
});
const { readable, writable } = await socket.opened;

// Join group (receiver side)
await socket.joinMulticastGroup("239.0.0.1");

// Send one packet — all group members receive it
const writer = writable.getWriter();
await writer.write({ data: new TextEncoder().encode("hello group") });

see also