Ethernet is pretty much dead

I still remember that an instructor of my college favored token ring and thought it was a better technology. He envisioned that if token ring had better marketing at the time, it would have dominated the market. The cost differences, he argued will disappear because of the huge economy of scale once a technology like that had become mainstream. But, it was too late. Ethernet had already dominated the market. I thought he was right.

It was eight years ago. After all, both of protocols vanished. People still refer to Ethernet all the time. However, is Ethernet really Ethernet anymore?

Since the market moved to 100Mbps, the concept of Hub phrased out. Because a hub does not wait until the whole frame (layer-two packet) to be transmitted before forwarding the frame, a hub has advantage on lower latency. However, it becomes less significant as the speed increased 10 folds. When the frame size remains the same, the latency is cut by 90%.

The beauty or uniqueness of Ethernet is actually happening in the layer 2. It sends frame after waiting a random period, send the frame, do collision detect, and resend if necessary. Now, Ethernet is connected port to port from a computer to the switch. All Ethernet are full duplex, Cat-5 twised pairs cable use different wire for transmission and reception. It essentially guarantees that no collision is possible. Say bye to aloha protocol that powered corporate network for more than 10 years.

Using switch actually bring significant performance advantage. In a busy network, the theoretical network thru put is about 57% (if I remembered it correctly). With full duplex and use of switch, we are getting pretty close to 200Mbps.

Most of the switch (at least entry level) use 5-port switch chip. The interconnection is likely to be Star Network. The Mac layer packet is forwarded exactly once to reach the destination.

8-Port Switch can be constructed by combining two chips. One port of each chip is connected on the circuit board level. Packet is forward 1 to 2 times. 16-Port can be constructed using 5 of such chips, with one port of each of the 4 chip connecting to a port on the 5 chip. Packet is forward 1 or 3 times.

Tree network won the final battle.