====== Media Layers - Wired Network Protocols ======
{{:en:iot-open:czapka_b.png?50| General audience classification icon }}{{:en:iot-open:czapka_m.png?50| General audience classification icon }}{{:en:iot-open:czapka_e.png?50| General audience classification icon }}\\
While the IoT ecosystem is usually considered to be composed of wireless devices, it is still possible to connect IoT solutions using a wired connection. 

When wireless-enabled SoCs were about to be delivered to the market (e.g. ESP8266), extension devices were already available for popular embedded systems, like Ethernet Shield for Arduino boards (figure {{ref>net_ethernet_shields}}).
<figure net_ethernet_shields>
{{ :en:iot-open:communications_and_communicating_sut:a000068_iso.jpg?200 | Ethernet shields for Arduino boards - image 1}}
{{ :en:iot-open:communications_and_communicating_sut:nano-w5100-ethernet-shield-network-expansion-board-nano-v3-0-top.jpg_640x640.jpg?150 | Ethernet shields for Arduino boards - image 2}}
<caption>Ethernet shields for Arduino boards</caption>
</figure>

Copper-based wired networks also bring an extra feature to the IoT designers – an ability to power the device via a wired connection, e.g. PoE (Power over Ethernet) – 802.3af, 802.3at, 802.3bt ((https://en.wikipedia.org/wiki/Power_over_Ethernet)). Long-distance connections may be implemented using optic-based, fibre connections, but those require physical medium converters that are usually quite complex, pretty expensive and power consuming; thus, they apply only to the niche IoT solutions. 

<note>The mentioned optical connections do not cover so-called LiFi, as those are considered to be of a wireless nature((https://www.techworld.com/data/what-is-li-fi-everything-you-need-know-3632764/)).</note>

A non-exhaustive list of some present and former wired networking solutions is presented in table {{ref>wired_protocols}}.
<table wired_protocols>
<caption>A Short Review of the Most Popular Wired Networking Standards</caption>
^ Name ^ Communication medium ^ Max speed ^ Topology ^ Max range (single segment, passive) ^
| Ethernet |Twisted pair: 10BaseT\\ Coaxial: 10Base2/10Base5\\ Fibre: 10BaseF  | 10 Mbps |Bus, Star, Mixed (Tree)  |10Base2: 0.5–200 m (185 m)\\ 10Base5: 500 m\\ 10BaseT: 100 m (150 m)\\ 10BaseF: 2 km (multimode fibre)  |
| Fast Ethernet |Twisted pair: 100BaseTx\\ Fibre: 100BaseFx  | 100 Mbps |Star  |100BaseTx: 100 m (Cat 5)\\ 100BaseFx: 2 km  |
| Gigabit Ethernet |Twisted pair: 1000BaseT\\ Fibre: 1000BaseX (LX/CX/SX)  |1000BaseT: 1 Gbps\\ 1000BaseX: 4.268 Gbps  |Star  |1000BaseT: 100 m (Cat 5)\\ 1000BaseLX: 5 km  |
|Local Talk (Apple) |Twisted pair | 0.23 Mbps |Bus, Star (PhoneNet)  |1000 ft  |
|Token ring |Twisted pair  | 16 Mbps | Star wired ring |22.5 m / 100 m (cable dependent)  |
|FDDI |Fibre  |100 Mbps (200 Mbps on two rings, but no redundancy)  |Dual ring  |2 km  |
</table>

The most popular wired networks are 10/100/1000 BaseT – twisted pair with Cat 5, 5e and 6 cables. They require the IoT system to implement a full TCP/IP stack to operate seamlessly with conventional Internet/Intranet/Extranet networks. Because it is usually out of the scope of standard Arduino Uno processor capabilities to implement a full TCP stack, there are typically dedicated processors on the network interfaces that assist the central processor or even handle all networking tasks themselves.