1. Introduction To Computers
Ethernet Networks

2. Ethernet Architecture
Ethernet is the most popular WIRED LAN standard
Wi-Fi is gaining in popularity, but it is not wired
There are lesser used architectures like Fieldbus
The ethernet standard defines:
The medium used
How data is packaged and accessed
Possible topologies
Cable length
Speed of network
The standard is updated routinely to introduce new technology

3. Network Interface Card
Every host on the network will need a NIC (Network Interface Card)
NICs will provide a MAC address for every host, which is a physical address assigned to that interface, and provide a transceiver, which takes the binary data of our host and applies it to our network medium
The type of transceiver, (and therefore NIC) will depend on the network media
Ethernet currently supports two connection media
Copper wire through ethernet and coaxial
Fiber Optic cable
Wi-Fi is NOT part of the ethernet standard

4. Networking Devices
If we are using a star topology (the most common topology in modern ethernet networking), we can use either hubs or routers when choosing a central connection point for our network
Hubs tend not to be used much, because switches provide a lot more functionality
Hubs will merely repeat a signal from one port onto the others, whereas a switch will use MAC addresses to forward the message to the right host
Routers will connect networks together, and provide a connection to a public network like the internet
Bridges will expand a network. The most common form right now is a wireless bridge which will add WIFI enabled devices to the same network the bridge is connected to

5. Topology
Older ethernet networks used a physical bus topology, with all devices connected to a central trunk
Newer ethernet networks use a physical star topology, with all of the host nodes connected to central device, such as a hub or switch
A logical bus topology is used when the network uses a physical bus topology or a physical star topology with a hub
A logical star topology is used when the network uses a physical star topology with a switch or router

6. Ethernet Naming Standards
To identify the speed of an Ethernet network we use specific Ethernet naming standards, which consist of numbers and letters
The number at the beginning denotes the transmission speed
Followed by the word BASE. This stands for baseband signaling, the type of signaling used on ethernet networks
After that, we have a dash followed by a letter. This letter defines the transmission medium and the maximum cable length

7. Ethernet Naming Examples
10BASE-T
10 megabit twisted pair, 100 meter max length
100BASE-TX
100 megabit twisted pair, 100 meter max length
1000BASE-T
1000 megabit twisted pair, 100 meter max length
10GBASE-T
10 gigabit twisted pair, 100 meter max length
10BASE-FL
10 megabit fiber optic, meter max length
100BASE-FX
100 megabit fiber optic, 412 meter max length
1000BASE-SX
1000 megabit fiber optic, meter max length (cable quality)
1000BASE-LX
1000 megabit fiber optic, 550 meter or 10km max length (mode)
10GBASE-SR / 10GBASE-SW
10 gigabit multimode fiber optic, 300 meter max length
10GBASE-LR / 10GBASE-LW
10 gigabit single mode fiber optic, 10km max length
10GBASE-ER / 10GBASE-EW
10 gigabit single mode fiber optic, 40km max length

8. Power Over Ethernet
Power over Ethernet (PoE) technology can be used to distribute electrical power along with network data on twisted-pair Ethernet cabling (CAT 5 or higher). Not fiber optic. Why?
Power is usually supplied by a PoE-enabled Ethernet switch. PoE is commonly used to power network devices that are located where physical access to a power outlet may not be available, like, a surveillance camera mounted on a tall pole
You can use a PoE injector to add PoE capability to regular non-PoE network links. They upgrade existing LAN installations to PoE, and provide a solution where fewer PoE ports are required. To upgrade a network connection to PoE, patch it through the PoE injector. Power injection is controlled and automatic

9. Duplexing
When using a hub all devices share the transmission media, and can either send or receive, but not both at the same time. This is called half-duplex
When using a switch, since there is no collision detection or chance for collision - devices can send and receive at the same time. This doubles the rated bandwidth, but requires NICs that are full-duplex capable and a switch with dedicated ports (one device per port)

10. Ethernet over HDMI and Ethernet over Power Line
With ethernet over HDMI networked entertainment devices can share their connection without additional ethernet cables. Look for devices with HEC functionality
Ethernet over powerlines allows for communication over existing AC power lines. A device is plugged into an AC power which uses multiplexing at a higher frequency than the AC power to another ethernet over power device. This can be helpful when you are unable to run ethernet into a specific room