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 ?
Multicast addresses are handled specially in routers and switches all over the world.
Changing that would require massive firmware updates everywhere to get this to work and we can’t even get people to adopt IPv6. Nevermind the complexity in figuring out to how manage IGMP group membership at the Internet scale.
Given the complexity with either change, its better to adopt IPv6 and use PeerTube. Multicast at the Internet scale won’t work and IPv6 is less work
Oh multicast’s not going to work on IPv6 either. From my research since writing the above, it has become clear to me when they say “it won’t scale”
they don’t mean some kind of Big O of N notation complexity or compute scaling, they mean economically
This crucial feature if it were unlocked, wouldn’t make the profits scale up,
they wouldn’t be able to say hey netflix, on our network multicast access is “this much” or facebook you CDN cache is “that much”
That’s what they mean with “scaling”, it’s not some kind of technical difficulty
If we had governments and they said “you will make it work OR ELSE” it could work, it could work very well.
I could send that 4 megabyte file to 500 person without paying a single bridge toll for it, just like in unicast.
We’re ALWAYS going to have to use someone else’s computer because that’s where the bridge toll is collected, if not in cash then in kind.
I don’t know who they is in the case, but let’s think about this for a minute.
Technically what do you need for this to work?
How many Multicast Addresses do you need? How are multicast addresses assigned? Can anybody write to any multicast address? How do I decide that 239.53.244.53 is for my file not your movie? How do we know who is listening? This is effectively BGP, but more tricky because depending on the answer to the previous question you may not benefit from any network block sizes to reduce the routing info being shared. How do you decide when to start transmitting a file? Is anybody listening? Does anybody care?
You seem latched on to assume that technically would work and haven’t asked if it is actually technically a good solution. P2P is going to work better than multicast
I don’t think there is a technical issue or any kind of complexity at issue here, the problem seems trivial even though I haven’t worked the details. It is moot since it’s broken on purpose to preserve “They’s” business model.
And “They” is the operators of the internet backbone, the CDNs, the ISPs
There protocols for dealing about what you’re asking Since multicast is a dead (murdered) technology, I can’t tell you exactly what does what but here they are
There would be many more of course, things that specifically resolve any unexpected issues that might arise from “actually existing multicast” in the hands of “the public”, which has never happened.
While I agree that P2P is the next best thing and torrents are pretty awesome, they are unicast and ultimately they waste far more resources, especially intercontinental bandwidth than multicast would.
Also multicast open protocol that might have developed if ISPs didn’t ruin multicast for everyone, would have steered the whole internet toward a “standard solution” in the same way that we all use the “same email system”. There would be one way that was “the way” of doing this one-to-many communication
To specifically answer your question, as far as routers are concerned, whenever a packet arrives, the router has to decide, WHICH of its WAN ports does the packet need to go to or does the packet need to be dropped.
From the point of view of the router, the whole internet is divided up in the number of WAN port it has and it sends the packet down the port with the shortest path to the destination host.
Multicast is a lot like that, the main difference is that the router MIGHT send the packet to more than one destination.
I think the solution is that receivers that wish to receive the multicast packets to a particular address (and port), from a particular source host, would subscribe to it. The literature mentions “multicast group subscription” I’m pretty sure this is already what this is for.
I think what this does is add branches in the routing table for the subscribed addresses in the multicast range. This tells the router about hosts that become part of the multicast group. I’m not sure if this is supposed to tell every router on the whole internet, or just the routers between the source and the destination host, but it gives the routers that need to know, where to send those packets pretty much in the same way as unicast, except with multiple destinations as specified in the multicast group subscriber list.
It’s really just unicast with extra steps, and not that many more steps, and those are all already baked in L3 switches silicon for decades. These protocols were designed to run on computers from the 1980s, I don’t believe for a minute that today we can’t handle that.
I’m explaining what the technical problems are with your idea. It seems like you don’t fully understand the technical details of these networking protocols and that’s okay but I’ve summarized a few non trivial technical problems that aren’t just people keeping multicast from being used. I assure you if multicast worked, big tech would want to use it. For example, Netflix would want to use it to distribute content to their CDN boxes and save tons of bandwidth.
But it does work if you run it on a parallel network, if you side step all the ISP’s toll bridges.
What you can’t do is negotiate with every ISP on the internet between you and your end users, giving a 30% cut to every one of them along the way. Especially since most of these ISPs were cable TV distributors in their previous life. They made sure to break it, to break it so good it becomes unimaginable that it could ever have worked in the first place.
And I think that has turned out just fine for netflix, the enormous deployment costs for their CDN means they have a moat, no small operator is going to be eating their lunch. Add to that brand name and platform power, the lack of standardized “one-to-many” infrastructureless broadcasting method, like “email” for broadcasting.
We’ll be stuck using Zuck’s computer to talk to each other pretty much forever now …