Ethernet

Ethernet is one of the interface standards for connecting devices.

It is standardized by the Institute of Electrical and Electronics Engineers (IEEE) as IEEE 802.3.

LAN (Local Area Network) cable is generally used for Ethernet communication.

LAN cables can be divided into UTP cables, STP cables, fiber optic cables, and coaxial cables.

■ UTP cable
UTP: Unshielded Twisted Pair
A set of two core wires is controlled by four sets, and it is also called a twisted pair cable.
One of the two has a positive voltage and the other has a negative voltage, and the signal "0" and "1" are distinguished by the change in voltage to send and receive data.
An RJ-45 connector is attached to the connection part.
Since it is not shielded, it is less susceptible to noise than STP cables, so it is cheaper than STP cables.

■ STP cable
STP: Shielded Twisted Pair
This is a UTP cable that has been shielded.
It is more resistant to noise than UTP cables, but more expensive than UTP cables.
UTP cables and STP cables that use RJ-45 connectors are divided into several standards according to transmission speed and transmission band.

Category	CAT5	CAT5e	CAT6	CAT6A	CAT6E	CAT7
Communication speed	100Mbps	1Gbps	1Gbps	10Gbps	10Gbps	10Gbps
Transmission band	100MHz	100MHz	250MHz	500MHz	500MHz	600MHz

■ Fiber optic cable
A cable that sends and receives data by transmitting light using glass or plastic.

Compared to cables that use copper wires, it has the advantages of better wideband communication and less noise, but it also has the disadvantage of being easily damaged.

The optical fiber is composed of a core in the center and a clad covering it.

Fiber optic cables are classified into two types according to the core diameter.

○ Single mode fiber
The core diameter is 10 μm or less.
Since light is difficult to disperse, it can be used for long-distance transmission, but it is a type that is difficult to construct.

○ Multimode fiber
The core diameter is 50 μm or 62.5 μm.
Since the core diameter is large, it is easier to install than single mode fiber, but the transmission distance is shorter.

■ Coaxial cable
There is one conductor in the center, which is surrounded by an insulator, an outer conductor, and an outer cover.

Originally used for connecting TV receivers and antennas, it is a cable used in standards such as 10Base5 and 10Base2.

Ethernet is divided into several standards according to communication speed and distance.

Standard	Communication speed	Cable used	Cable standard	Distance
10BASE-T	10Mbps	UTP/STP	CAT3 or higher	100m
100BASE-TX	100Mbps	UTP/STP	CAT5 or higher	100m
1000BASE-T	1000Mbps	UTP/STP	CAT5e or higher	100m
1000BASE-TX	1000Mbps	UTP/STP	CAT6 or higher	100m
10GBASE-T	10Gbps	UTP/STP	CAT6A or higher	100m
100BASE-FX	100Mbps	Optical cable	Multimode fiber	2km
			Single mode fiber	20km
1000BASE-SX	1000Mbps	Optical cable	Multimode fiber	550m
1000BASE-LX	1000Mbps	Optical cable	Multimode fiber	550m
			Single mode fiber	5km
10GBASE-SR	10Gbps	Optical cable	Multimode fiber	300m
10GBASE-LR	10Gbps	Optical cable	Single mode fiber	10km
10GBASE-ER	10Gbps	Optical cable	Single mode fiber	40km
1000BASE-CX	1000Mbps	Coaxial cable	-	25m
10GBASE-CX4	10Gbps	Coaxial cable	-	15m