I found the multicast registery here.

https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml

I already knew that addresses between 224.0.0.1 and 239.255.255.255 are reserved by multicast.

Obviously multicast could be immensely useful if used by the general public, it would obsolete much of facebook, youtube, nearly all CDNs (content delivery networks), would kill cloudflare and company’s business model and just re-arrange the internet with far reaching social implication.

So, why hasn’t all these multicast addresses been converted in usable private IPv4 unicast address space ?

  • bandwidthcrisis@lemmy.world
    0·
    3 months ago

    I see I misunderstood how you mean this to work, that routing would handle sending data only to subscribers. I was imagining that it mean a simple LAN broadcast using a packet with the subnet bits all set (e.g. 192.168.255.255). I think that it’s more analogous to a mailing list distribution, but for general data/streams?

    But your earlier example of downloading the cat video still fails unless many people request the video at the same time (otherwise you’re multicasting to one). What happens if I watch the video on my phone while out, then watch it again on my laptop at home? It will still need sending twice.

    Wouldn’t a more efficient approach just be to have something like ipfs with lots of local caching?

    • interdimensionalmeme@lemmy.mlOP
      0·
      3 months ago

      It’s not “video-on-demand”, you don’t subscribe to a file but to an address, the multicaster sends the file or stream or message when they’re ready, you receive them if you’re listening, everyone subscribed gets the same series of packets. It’s the only benefit that multicast really has over unicast, the sender just sends the packet once. There’s no server, no caching, no repeats. Direct from you to them and it can work for everything.

      • bandwidthcrisis@lemmy.world
        1·
        3 months ago

        So when a video is created it is immediately sent to subscribers?

        In that case, for things to be sent once, it relies on the receivers always being online. That doesn’t work if my laptop is closed at the time.

        That’s why I’m thinking that it needs online caching to work. Or everyone has a cloud server that handles sending and receiving while they’re not online.

        In fact, that starts to sound like everyone running their own personal lemmy-like instance, to which their friends subscribe.

        And in that case it wouldn’t matter if messages were sent more than once, each person’s server would handle it.

        • interdimensionalmeme@lemmy.mlOP
          1·
          3 months ago

          The information could be live streamed from the camera or from a recording, that doesn’t make a difference. It could also be ANY data, not just video.

          Also, yes, if you are not listening for the packets, then you will not receive them later. There is no servers between the sender and receiver, this means no gatekeeper, no middleman, it’s a democratization of broadcast without intermediaries.

          The only reason it is more efficient is because of how direct it is.

          Before the internet we had TVs which, if they were not turned on, could not store and receive any of the video stream being broadcast, it’s a lot like that. You didn’t ask the TV station to send you a video file, they sent it out regardless and you listened to it or you didn’t.

          The problem with caching or storing anything, is now you’re back to need one connection per receiver, you’re no longer sending out a single copy, you have to send 500 hundred copies if 500 people want it, that takes far too much resources.