Ethernet

Introduced in 1973 by Robert Metcalfe in his PhD thesis. Named after ether the imaginary substance. Became IEEE 802.3 Standard.

Dominant in the industry because:

• cheap
• simple (compared to token LANs, ATMs)
• good performance (10Mbps - 10Gbps)

Frame structure

Includes:

• preamble
• destination address
• source address
• type/length field
• data/payload
• frame check sequence (FCS)

Preamble

7 bytes with pattern 10101010 followed by one byte with pattern 10101011. Used to synchronize receiver, sender clock rates.

Address

6 byte source and destination MAC addresses are included.

Type

Indicates the higher layer protocol.

Examples: IP, Novell IPX, AppleTalk.

CRC

To check if there are any errors with the frame. If so, the frame is discarded.