Please correct me if I’m wrong, might have breathed in too many soap fumes.
Token Ring sends the packets to every node by passing it from one node and if that node is not the recipient it passes it on to the next node.
Memos were created the day before with a list of recipients then it was passed around till everyone on the list had read it.
I think token ring is a data link layer technology that controls transmission access over the physical connection. Like early non-switched Ethernet, computers are connected in parallel to the same wires but instead of collision detection and random delays, which caused congestion and serious overhead on busy networks, a “token” is passed around and determines the right to “speak”. Everyone listens at the same time and starts receiving packets when addressed. If the computers were literally wired in series like a looping daisy chain, the failure of one would destroy message propagation. Instead, if the token-bearing computer or disconnects from a token ring network, the token is presumed expired after a short while and a new token-bearer is chosen. It’s like a kindergarten activity where you sit around in a circle and need to hold the ball to speak, passing it around. It doesn’t matter who you’re addressing, you can even broadcast, but that’s handled by a higher-level protocol.
As for memos, I have never used them and they seem extremely inefficient.
Edit: looks like Token Ring is actually more physical than I thought, with special cables connecting computers in series, so you may be right. That sounds really stupid as a thing to build a network on, it’s easy to cut it in half by disabling just two computers, antithetical to the internet’s resiliency principle.
Edit edit: my original understanding was right, the literal cable ring is obsolete for good reason. I still don’t get the role of a MAU in the star topology unless it’s just needed for old NICs to understand virtual tokens.
The MAU turned a physical star topology into a logical ring topology.
Moving to star was more of an assistance to physical installs
My point is, if you have a shared medium anyway, you can get rid of the MAU by having nodes manage the (virtual) token themselves, basically take limited-time turns based in some order like ascending MAC addresses. You could then wire the cable in any way you want with unlimited junctions, taps, whatever as long as you created a graph where all nodes are connected to each other. The entire point of a token ring is to manage a shared medium (that is, a single pair of wires, either UTP or coax, which can efficiently be wired along the shortest, possibly branching path) because if you have to use a direct connection from every endpoint to an MAU in a star topology, you could just have an Ethernet switch anyway.
The whole point behind it was that everything was too slow to handle it efficiently themselves in an uncontrolled manner. When networks and computers got faster we started using ethernet.
Yes, and it’s also that switches got cheaper so most new installations only connect two nodes with a single physical conductor.
The whole point was that cs/ma (check if anyone is talking while you’re talking) was a competing strategy to token ring (everyone can talk in their turn).
You could lose most of your bandwidth under contention with csma, it scaled poorly and routers/switches were crazy expensive because they needed to have memory to buffer packets at full flow.
Somebody made an integrated switch ASIC and the price plummeted and suddenly every network was switched.
My memory of token ring is vague, but I think it was originally a ring in series as you said - however token ring switches (that isn’t what they were called) also existed, which was the “modern” way of writing up a token ring network.
Yeah, see the pic in the thread. The “switch” (MAU, Media Access Unit) seems redundant to me though, based on what I read I would expect the network interface cards to create a functional ring on their own over a shared medium. Maybe the old cards for ring-topology networks only worked in that one mode and the MAU made them compatible by pretending they were part of a physical ring, cutting computers out of it if they turned off.
Yes, I think that’s probably how it worked.
😜 I love Cunningham’s law. Yeah token ring sucked hard we used it with bnc coax cables and vampire taps at school.