Overview of Ethernet

• The most common Local Area Networking (LAN) technology in use today.

• Invented by Bob Metcalf at Xerox Palo Alto Research Center in 1973.

• Slang name for 2 similar, but seperate LAN technologies.

• Dec / Intel / Xerox Ethernet 2.0

• Operates at 10 Million Bits per Second (10 000 000 bps).

• Specifies a format (called a frame - has fields like a database record) for the information travelling along the cable.

• Specifies thick (about the size of your index finger) coaxial cable.

• Maximum length of 500 meters.

• IEEE 802.3

• Also operates at 10 Million Bits per Second (10 000 000 bps). There is also a new standard which operates at 100 Million bits per second.

• Specifies a slightly different frame format than DIX Ethernet 2.0 - only one field is different.

• Specifies and names combinations of IEEE 802.3 frame format operating over different cable types :

• 10Base5 - IEEE name for DIX Ethernet 2.0.

• 10Base2 - IEEE 802.3 operating over thin RG-58 coax (size of a drinking straw) with a maximum length of 185 meters.

• 10BaseT - IEEE 802.3 operating over unshielded twisted pair cable with a maximum length of 100 meters.

• 100BaseT - IEEE 802.3 operating over unshielded twisted pair cable with a maximum length of 100 meters, at a speed of 100Mbps.

• DIX Ethernet 2.0 and IEEE 802.3 are somewhat interoperable.

• An "ethernet" network card can understand either frame type, independant of the physical cable type the LAN is made of.

• Multiple frame types can be operating on the LAN at the same time.