CCNA - Ethernet

Ethernet is the standard technology used for wired local area networks. It defines how devices connect and communicate over copper or fiber.

• Ethernet is the base of most LANs
• It uses frames, not packets
• MAC addresses are used at Layer 2
• Switches forward Ethernet frames
• It can run over copper or fiber
• Ethernet is cheap, simple, and widely used

Ethernet standards define speed, cable type, and transmission method. Common examples:

• 100BASE-TX
• 1GBASE-T
• 10GBASE-SR
• 10GBASE-LR

Copper

• cheaper
• common for short distances
• can carry PoE

Fiber

• longer distances
• immune to EMI
• more expensive

• Frame = Ethernet data unit
• MAC address = Layer 2 identifier
• MTU = maximum frame payload size
• Duplex = send/receive behavior

• PoE
• Switch & Router
• OSI - TCP/IP