CSMA/CD Ethernet

Local Area Network (LAN) developed at Xerox Palo Alto Research Center (PARC) in mid-1970s became IEEE 802.3 standard. 10 Mb/s data rate over shared medium, 1024 maximum number of nodes, 1500 m maximum length. Uses Carrier Sense, Multiple Access with Collision Detect (CSMA/CD).

Carrier Sense - all nodes can distinguish between idle and busy link

Collision Detect - node listens for interference from other nodes as is transmits

Repeater used to

forward signals

Floor 2

Floor 1

10BaseT segment length ~ 100 m

Coax cable acts as a bus

Repeater has

internal bus

Host

1

Host

5

Host

2

Host

3

Host

4

Host

8

Host

7

Host

6

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