Ethernet: The Local Network Standard
Bob Metcalfe's invention at Xerox PARC became the dominant local area network technology. From 2.94 Mbps to 400 Gbps, Ethernet evolved from a single shared cable to sophisticated switched networks.
The Problem Ethernet Solved
In the early 1970s, computers were isolated machines. Bob Metcalfe at Xerox PARC realized that if multiple computers could share a common cable, they could communicate and share resources like printers and storage. His breakthrough was the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol.
How CSMA/CD Works
On a shared Ethernet network (now called a "collision domain"), all computers compete for the same cable. Before transmitting, a computer "listens" to see if the cable is busy (Carrier Sense). If two computers transmit simultaneously, the voltages collide (Collision Detection). Both computers then wait a random time before retrying.
Evolution of Ethernet Media
- 10BASE5 (1983): Thick coax cable, up to 500m, vampire taps
- 10BASE2 (1988): Thin coax (Thinnet), BNC connectors, 185m
- 10BASE-T (1990): Twisted pair, Cat3/Cat5, RJ45, 100m
- 100BASE-TX (1995): Fast Ethernet, Cat5, 100 Mbps
- 1000BASE-T (1999): Gigabit, Cat5e/6, 1 Gbps
- 10GBASE-T (2006): 10 Gbps, Cat6a/7
The Switched Ethernet Revolution
The introduction of Ethernet switches in the 1990s transformed LANs. Instead of a shared cable, each device gets its own dedicated connection to the switch. Collisions became extinct, and full-duplex communication doubled throughput. Managed switches added VLANs, QoS, and network segmentation.
Ethernet Today
Ethernet dominates local networks—homes, offices, data centers, and industrial facilities. While Wi-Fi handles client connections, Ethernet remains the backbone for its reliability, security, and ever-increasing speeds. The latest standards support 400 Gbps and even 1.6 Tbps for hyperscale data centers.