As switch Ethernet ports became less expensive, switches replaced hubs in the
wiring closet. Initially, when switches were introduced, network administrators
plugged hubs (containing multiple hosts) into switch ports. But eventually, it
became cost-effective to plug the hosts directly into a switch port. This
arrangement gives each host its own dedicated Ethernet and removes the possibility
of collisions. Because a dedicated switch connection has only two devices
(the switch and the host), you can configure an Ethernet switch port as full
duplex. This means that a device can receive incoming traffic and transmit
traffic simultaneously. End stations have considerably more bandwidth when
they use switches. Ethernet can run at multiple speeds: 10 Mbps, 100 Mbps,
1 Gbps, and 10 Gbps. Therefore, switches can provide connectivity at these
speeds. However, network applications and the web create considerably more
network traffic, reintroducing new congestion problems. Switches can use
quality of service (QoS) and other mechanisms to help solve the congestion
issue.