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 ?
They are still in use as multicast. Typically it’s for local traffic.
I don’t think multicast over the internet would have taken off as multicast requires all routers between the source and any destinations to be multicast aware. Each would need to keep track of the subscriptions, meaning more resources that would mean higher cost. There was also less interest as one of the pluses of internet delivery was that delivery was on demand.
In the end cdns were going to be created anyway for static content and streaming could just use the same systems to produce effectively the same improvements.
But your next question would be why have they not done it for the experimental range.
Well, everything knows those packets are not on the internet so will block them. If you want to ask the internet to upgrade everything for that, well just ask how the ip6 upgrade is going.
They need to do it with unicast, which necessarily takes more resources to do. Think of it, 500 unicast stream or a single multicast stream, it’s not even close how much less computing power multicast takes.
Make no mistake, multicast is broken by choice. Working multicast is “contempt of business model”, it would cannibalize CDN profits to become as free as unicast.
One crucial distinction is that you as an individual, will Zuck’s permission to use their system, in their way, in their rules.
And of course by “Zuck” I mean, “the cloud” aka “someone else’s computer”, which was not needed if multicast did just work, another enforced cloud dependency
1/16 of all IPv4 addresses were reserved for PUBLIC USE but they remain firmly in the grasp of private hands, private hand that want you to pay the toll and obey their masters
My GPON FIBER ISP said “we’ll probably never implement IPv6”, even though every single piece of equipment on their network supports it, even their horrible rebadged Huwawei routers
It won’t work and it will keep not working until we make them.