Media Layers – Wired Networking
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. In this chapter, we do not present communication protocols that are short distant one designed to connect sensors to IoT device, like I2C, SPI, Serial, etc. Those are described in chapter “4.2. Embedded Systems Communication Protocols”.
When wireless-enabled SoCs where about to be delivered to the market (i.e. ESP8266), there were already available sorts of extension devices for popular Embedded systems, like i.e. Ethernet Shield for Arduino boards.
Cooper based wired networks also bring an extra feature to the IoT designers – an ability to power the device via a wired connection, i.e. PoE (Power over Ethernet) – 802.3af, 802.3at, 802.3bt [1]. 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. Please note, mentioned optical connections do not cover so-called LiFi, as those are considered to be wireless [2].
A non exhaustive list of some present and former wired networking solutions are presented in the Table 1.
Table 1: A Short Review of the Most Popular Wired Networking Standards
| 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 |
Nowadays, the most popular wired networks are 10/100/100BaseT – twisted pair with Cat 5, 5e and 6 cables. They require the IoT system to implement 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 full TCP stack, there are typically dedicated processors on the network interfaces that assist the central processor or even handle all networking tasks themselves.
