Ethernet

Frame Structure

Preamble	Dest addr	SRC addr	Type	Data	CRC

Preamble: 8 bytes
addr: 6bytes(MAC addr)
type: indicate higher protocol
CRC: error check

CSMA/CD

exponential Backoff

first collision: $K \in {0, 1}$
after second collision: $K \in {0, 1, 2, 3, . . .}$
after 10 or more: $K \in {0, 1, 2, . . ., 10, 16, 32, 64, . . ., 1024}$