Traditionally, network managers have used bridges or routers to segment their networks. Many people have discovered that, for a local network, the difficulty of installing and managing routers is not worth the effort, and they've made the jump to switches. A few network managers have gone so far as to give each user a dedicated Ethernet segment, although such special treatment is usually reserved for the servers. Another solution to the bandwidth crunch is to increase the speed of the media. Ethernet is inherently half-duplex in that one wire in the 10BaseT pair is used to transmit data and the other is used to receive data.
Packets travelling on both wire pairs at the same time indicate a collision.
The collision-detection circuitry becomes unnecessary, and data can travel on that wire. Full-duplex is also suitable for Token Ring, although Token Ring networks don't suffer the same performance bottlenecks as Ethernets do. That second wire pair can be used to carry data. Users of older or less-sophisticated Ethernet cards aren't as fortunate. Vendors are charging little or no premium for full-duplex transmission.