Ethernet Fundamentals

Overview of LANs

The term Ethernet refers to a family of LAN standards that define physical and data-link layers of the world’s most popular wired LAN technology. The cabling, the connectors of the cables, the protocol rules, to create an Ethernet LAN.

Ethernet Physical Layer Standards

Ethernet supports a large variety of options for physical links, includes many standards for different kinds of optical and copper cabling, and speeds as far as the types and length of the cables.

UTP cabling transmits data over electrical circuits via the copper wires inside the cable. Fiber-optic cabling, allows data to send, over a light in glass fiber in the center of the cable. Optical cables allow longer cabling distances between nodes.

Cables Types of Ethernet

Speed	Name	Standard Name	IEEE Standard	Type & length
10 Mbps	Ethernet	10Base-T	802.3	Copper, 100 Mtr
100 Mbps	Fast Ethernet	100Base-T	802.3u	Copper, 100 Mtr
1000 Mbps	Gigabit Ethernet	1000Base-LX	802.3z	Fiber, 5000 Mtr
1000 Mbps	Gigabit Ethernet	1000Base-T	802.3ab	Copper, 100 Mtr
10 Gbps	10 Gig Ethernet	10GBase-T	802.3an	Copper, 100 Mtr

Ethernet Data-Link Layer

Ethernet uses the same data-link layer standard over all types of physical links. That standard defines a common Ethernet header and trailer, over a UTP or any kind of fiber cable, regardless of speed, the data-link header and trailer use the same format.

While the physical layer standards emphasize sending bits in form of electrical or light signals over a cable.

Ethernet LAN is a combination of user devices, LAN switches, and different kinds of cabling. Each link can use different types of cables, at different speeds.

They all work together to deliver Ethernet frames from the one device on the LAN to some other device.