Wired Ethernet

Overview

• Ethernet is the most common form of LAN today.
• The Star-Wired Bus topology is the most prevalent, though the bus topology is not completely obsolete.
• Ethernet comes in various forms based on the medium used, transmission speed, and technology.
• Ethernet can also be used to transmit power using Power over Ethernet (PoE)
• Medium Access Control Protocols is used by a workstation get it’s data onto the Local Area Network (LAN) Medium

Evolution of Ethernet Speeds

• CSMA/CD initially operated at 10 Mbps.
• 100 Mbps was introduced later.
• Most NICs today are 10/100 Mbps.
• 1000 Mbps (1 Gbps) was introduced subsequently.
• 10 Gbps is now being used in high-end applications.

Features of 1000 Mbps Ethernet

• Full-duplex transmission eliminates collisions.
• Prioritization of traffic is possible using the 802.1p protocol.
• Star or mesh topologies can be employed, especially for trunk lines.
• Delay-sensitive traffic (e.g., voice, video) can be separated from loss-sensitive traffic.

Ethernet Standards Table

Standard	Speed	Duplex	Topology	Key Features
10 Mbps	10 Mbps	Half/Full	Star/Bus	Legacy networks
100 Mbps	100 Mbps	Half/Full	Star/Bus	Common NICs today
1000 Mbps	1 Gbps	Full	Star/Mesh	High-performance, prioritization possible
10 Gbps	10 Gbps	Full	Star/Mesh	High-end applications, advanced traffic management