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 ?

    • interdimensionalmeme@lemmy.mlOP
      2·
      17 days ago

      We organize multicast nationally and globally like we do RF band plans. Some addresses are reserved to stream advertising that anyone can pickup with the global, national, regional, metropolitan, city, town, street levels.

      Eligible host subscribe, or advertise their “subscription” to a particular address (and port, we’ve got 65536 ports and most communications between two hosts use just one)

      The subscription are broadcast within their scope, pooled into distributed tables copied in bulk between routers. It’s simple association of multicast groups and subscribed hosts.

      The end result is that at minimum all routers existing between an host and their subscriber have a copy of the multicast group membership for that address.

      When a packet to that address arrives on any router in between, the route trigger and the router sends it down each of its WAN port that has a unicast subscriber down stream.

      That’s basically the multicast process with just a little improved protocols and caching for effciency.

      I say a little improved, but I think it’s already all there, there burned into the silicon already. It’s just a matter of turning it on and politicians putting on the screws on ISPs to make them play nice.

      The bulk of it is already in these protocols

      IGMP (Internet Group Management Protocol)
PIM (Protocol Independent Multicast)
PIM Sparse Mode (PIM-SM)
PIM Dense Mode (PIM-DM)
MSDP (Multicast Source Discovery Protocol)
MBGP (Multiprotocol BGP)

      There might be still a bit of glue to get there, but on the whole, on a technical front this is less technology than it took to get bittorrent to work. And bittorrent works, really really well !

      We’re going to need more client side software, but that will come as soon as “multicast works” because it just didn’t make sense to make global multicast stream browser when there was no global multicast

      We’re talking stream browsers, viewer clients for all kinds of media types, video viewer “tv” “radio”, text streams, notification streams, things we cannot even imagine yet

      And we’ll need a non-censorious curation system, anonymous cryptographic crowdsourced reputation system, that’s “letsencrypt” on steroids. Voting and beyong-voting systems of likes, dislikes, superlikes, blocks, bans, replies, forward, crosspost all the social media stuff but floating mid-air without a single server or janitor managing it all, just the same abuse prevention system that deal with DDOS and SPAM, everything else is fair game and section 230 protected.