On Sun, 22 Mar 2020 19:17:59 +0000 Grant Taylor via NANOG <nanog@nanog.org> wrote:

What was wrong with Internet scale multicast? Why did it get abandoned?

There are about 20 years of archives to weed through, and some of our friends are still trying to make this happen. I expect someone (Hi Lenny) to appear any moment and mention AMT. So my take isn't universally accepted, but it won't be too far from what you'll hear from many. Brief summary off the top of my head: 1. Complexity. Both in protocol mechanisms and the requirements in network devices (i.e. snooping, state, troubleshooting). 2. Security. Driven in part by #1, threats abound. SSM can eliminate some of this and you can design a receiver-only model that removes most of the remaining problems - congratulations you just reinvented over the air broadcast TV. Even if you don't do interdomain IP multicast, you still may be at risk: <https://ccronline.sigcomm.org/wp-content/uploads/2017/01/p27-sargent.pdf> 3. Need and business drivers. Still far from compelling to build and support all this to make it worthwhile for all but a few niche environments. Support and expertise in this area is also very thin. Your inquiry demonstrates this. I stopped teaching it to students. What remains is becoming even less well supported than it has been. There is almost no interdomain IP multicast monitoring being done anymore. There is scant actual content being delivered, all the once popular stuff is gone. The number of engineers who know this stuff are dwindling and some that do know something about it are removing at least some parts of it: <https://tools.ietf.org/html/draft-ietf-mboned-deprecate-interdomain-asm-07> John