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Ethernet Networking

although this might happen one day, justifying the cost of that network
today really is pretty unreasonable. But if you mix and match the different
types of Ethernet media methods available today, you can come up with a
cost-effective network solution that works great.

The EIA/TIA (Electronic Industries Association and the newer Telecom-

munications Industry Association) is the standards body that creates the
Physical layer specifications for Ethernet. The EIA/TIA specifies that Ether-
net uses a registered jack (RJ) connector with a 4 5 wiring sequence on
unshielded twisted-pair (UTP) cabling (RJ-45).

Here are the original IEEE 802.3 standards:

10Base2 10Mbps, baseband technology, up to 185 meters in length.
Known as thinnet and can support up to 30 workstations on a single seg-
ment. Uses a physical and logical bus with AUI connectors. The 10 means
10Mbps, Base means baseband technology, and the 2 means almost
200 meters.

10Base2 Ethernet cards use BNC (British Naval Connectors) and T-Connectors

to connect to a network.

10Base5 10Mbps, baseband technology, up to 500 meters in length.
Known as thicknet. Uses a physical and logical bus with AUI connectors.
Up to 2500 meters with repeaters and 1024 users for all segments.

10BaseT 10Mbps using Category 3 unshielded twisted-pair (UTP) wir-
ing. Unlike the 10Base2 and 10Base5 networks, each device must connect
into a hub or switch, and you can only have one host per segment or wire.
Uses an RJ-45 connector with a physical star topology and a logical bus.

The "Base" in the preceding network standards means "baseband," which is

a signaling method for communication on the network

Each of the 802.3 standards defines an Attachment Unit Interface (AUI),

which allows a one-bit-at-a-time transfer to the Physical layer from the Data
Link media access method. This allows the MAC to remain constant but
means the Physical layer can support any existing and new technologies. The
original AUI interface was a 15-pin connector, which allowed a transceiver
(transmitter/receiver) that provided a 15-pintotwisted-pair conversion.

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