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Comment by cimnine | Hacker News Reader

Yes. Yet maybe the switches aren't VLAN aware either. Then – as far as I understand – VLANs would not have helped here either.

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IP multicast only works over the broadcast domain, so VLANing off the speakers would work. You’d need multicast routing enabled on your routers to move multicast traffic between VLANs.

IP multicast routing and internetworking is a thing. There used to be working one to many internet TV based on multicast in the 90s (was called Mbone). There's contemporary experimental use of routed multicast on public internets too (see eg https://meetings.internet2.edu/2019-technology-exchange/deta...)

edit: seems the IETF are currently in process of deprecating any-source multicast and recommending people focus on keeping single-source multicast working well in as many networks as possible: https://datatracker.ietf.org/doc/rfc8815/

Oh, IP TV you get from you ISP in France today is totally multicast based ! Not on public internets tho, yes, that's limited to the ISP network.

I was on the local MBone segment at the NASA base (though a Navy installation) I worked at in the late 90s. It pretty much worked like you would expect, some interesting things that happened:

- Multicast frames caused our FDDI switches to reboot, had to filter everywhere those were used

- When setting up our local CoffeeCam, we used Multicast video stream -- this would have been accessable from anywhere (which would cause a security incident, no one can know when the Rear Admiral drinks coffee) so we were careful to monitor outbound advertisements and used a low TTL

- SDR, VIC, VAT, RAT, and all those other tools for doing multicast stuff worked but were very clunky

- NASA TV was broadcast over the MBone and times they would go to break in other broadcasts were continued to stream, I think various cameras were available

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