EthernetLANs

Ethernet LANs are local area networks that use Ethernet technology to connect computers and other devices within a limited area, such as a building or campus. They are built on the IEEE 802.3 family of standards and rely on MAC addresses to deliver frames over a wired medium. Ethernet supports multiple media, including copper twisted-pair cables and fiber optic cables, with distances that vary by medium and speed.

Historically, Ethernet began as a shared coaxial cable using CSMA/CD access, but modern Ethernet is predominantly switched. switches create separate collision domains and a star topology, enabling full‑duplex communication and higher performance. This shift has driven successive speed upgrades from 10 Mbps (10Base-T) to 100 Mbps (100Base-TX), 1 Gbps (1000Base-T), 10 Gbps (10GBASE-T), and beyond to 40/100 Gbps in data-center environments.

Media and distance: copper twisted-pair (commonly Cat5e/Cat6) supports up to about 100 meters at most speeds; fiber optics (multi‑mode and single‑mode) enable much longer links. Power over Ethernet (PoE) can supply power to devices such as IP phones, cameras, and wireless access points over the same cable used for data.

Typical Ethernet LAN deployments include switches at the network core, access switches at the edge, and NICs in hosts, with routers providing connections to other networks. VLANs are commonly used to segment traffic, and wireless access points can be integrated for hybrid wired/wireless networks. Hubs have largely been deprecated in favor of switched networks.

Ethernet LANs generally provide predictable, low-latency wired connectivity and are complemented by wireless LANs for mobility. Security is achieved through network design, access control measures, and, where appropriate, VLANs and encryption techniques, rather than Ethernet itself providing encryption.