this post was submitted on 26 Oct 2024
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That's not how token ring worked. The token controls which node is allowed to transmit over a shared medium. Every node saw every packet and made it's own determination of relevance.
That's what I thought too unless the pic (left) literally is how cables are arranged??
My understanding was a shared medium (say, all computers in parallel on a single UTP), where they pass a virtual token "packet" that assigns the right to transmit while anyone receives if addressed, like a ball between kindergarteners sitting in a circle.
The pictured ring topology (left) makes it seem like everyone can only talk to a computer one over, which seems awful for efficiency and resilience, while the pictured star topology (right) introduces an authority figure (MAU is like a kindergarten teacher that decides who walks around and gives the ball to whichever child they think should speak next). Both seem inherently worse than Ethernet - left can be completely broken by disabling one or two nodes while the right one is just a switched network with less throughput.
Back when token ring was designed normally networks would use coaxial cables for communication. No matter if it ran ethernet, token ring or something else, everybody would share basically a single cable. The cable would have T connectors inserted to connect a computer and the end of the cable needed something to terminate it. It didn't need to be a single line, you could have splits and even a star like design, although there were limitations.
And you are right, any disruption anywhere on the line meant the network would go do. That might be someone removing the termination cap on the end, or simply the line being broken somewhere. However because computers were usually connected using T splitters, it didn't really matter if the computer was connected or not. But the connection not being terminated properly could be an issue. Especially if there was another cable connected to the T before being connected to the computer.
Normally in a room the cable would be laid out like a ring although it usually wouldn't be a closed ring, but instead terminated on one end. This meant each computer would be connected to its direct neighbors, but this wouldn't be an active thing. It wasn't like the computer could only transmit to its neighbors and then they needed to pass it on. It was like a shared line, where everyone could transmit and every computer would receive everything transmitted.
When everything switched over to the regular twisted pair cables we know today, it didn't really change from a communications point of view. Every computer wasn't connected to their neighbors but instead to a hub, but just like before anything anyone transmitted could be received by anyone on the network. It wasn't until much later when things like switches became commonplace and not everyone got all the traffic.
We had one case where a line had been strung over a lighting ballast in a janitor closet. Whenever that light was turned on the whole network would go down. Since it was only on for a few minutes intermittently it was a nightmare to find. You would go looking for the a bad terminator and the network would come back before you checked a single one. Good times.
There definitely are good reasons why Ethernet won out over token ring, but there are scenarios where token ring was better. Before modern bridges, Ethernet could struggle with collisions if a network were too highly utilized - especially if nodes were physically spread out.
As for the diagrams, it can sometimes be confusing when it's not made clear what is being represented. Physical and logical topologies can be mixed star and bus and matched in different ways, and diagrams don't always make clear to which they refer.