Ethernet networks and Token Ring networking coexisted in data centers past, but Ethernet was efficient and less expensive, scaling well beyond Token-Ring's 16 MBps data rates. And Ethernet is still scaling as users demand more data.
Token Ring network architecture operated like a round robin -- passing a token around a ring of interconnected devices until a node needed to exchange data. Ethernet networks introduced a collision approach; nodes simultaneously competed for access to the wire. The result was a chaotic yet efficient use of the network, and early coaxial cabling was replaced by much less expensive twisted pair cabling. Ethernet was popularized by then-fledgling 3Com from the 1970s into the 1980s. The IEEE standardized Ethernet in the mid-1980s.
As contention for use of the wires and higher-bandwidth applications caused serious latencies, Ethernet speeds grew to 100 MBps, then to GBps. Enterprise data centers adopted GigE as a network backbone. Today, GigE is the common standard network adapter for almost every server or endpoint computer. Data center servers often combine GigE with TCP offload engine network adapters to handle high network traffic.
The future holds even faster Ethernet standards. While 10 GigE is primarily used for high-bandwidth applications, expect it to slowly filter down to individual servers and endpoint systems. Speeds of 40 GigE and even 100 GigE are currently standardized in IEEE 802.3ba and several subsequent additions. Those high-speed Ethernet technologies primarily are based on optical fiber (though 40 GigE is possible over Category 8 twisted pair cable) and await broad adoption across the data center, paired with innovations like software-defined networking.