What Is an Ethernet Switch?

What is Ethernet?

Ethernet technology is designed to solve the problem of packet collision in a shared network by having network-connected devices follow a set of rules that allow devices to talk to each another without talking over each other. These network-connected devices are physically connected with a cable to an Ethernet switch that then manages the flow of data between devices, applications, data, cloud services and the internet. 

More formally, Ethernet is a common name for the IEEE 802.3 standard based on the Carrier Sense Multiple Access/Collision Detection (CSMA/CD) protocol, which defines when to transmit and what is to happen if a collision is detected, as well as endpoint addressing, transmission speeds, and media. The IEEE 802.3 media standards focus on cable type (coaxial, twisted-pair and fiber), bandwidth capacity (10 Mbps to Tbps) and transmission distance.

Ethernet has evolved dramatically since its first application and today is the de facto protocol for IP-based networks and the internet. Ethernet switches have also become the common network switch type and foundational technology for most networks.

How is Ethernet different from Wi-Fi?

Wi-Fi can be seen as an extension to an Ethernet access network allowing wireless connections to an Ethernet network. Wi-Fi allows the freedom of mobility without the need to connect with a network cable.

From a network point of view, typically Wi-Fi requires a wireless access point device to act as the interface to the network. The end device is connected to the access point and the access point is connected to, or is part of, the Ethernet switch instead of being connected directly to the switch by physical cable.

Wi-Fi and Ethernet are outlined by separately in the IEEE 802 protocols, with Ethernet defined by IEEE 802.3 and Wi-Fi defined by 802.11.

How do Ethernet connections differ from Wi-Fi?

From a user perspective, an access Ethernet connection requires a physical cable and provides a dedicated link from the switch to the end device with bandwidth up to the speed of the connected port. Wi-Fi connections are wireless and allow devices to be located anywhere that can receive a Wi-Fi signal but share the bandwidth of the connecting Wi-Fi access point with other devices connected to the same AP.

Are an Ethernet switch and hub the same?

No. While they are both examples of data network hardware, a hub is a Layer 1 device, which is part of the physical transport layer and acts as a broadcast/aggregator but does not manage any of the traffic.  

An Ethernet switch manages the flow of data, directing data it receives in one port to another port based on information in a data packet’s header, namely the sending and receiving MAC addresses. The switching process significantly improves the efficiency of the network as opposed to a hub. 

Can Ethernet switches act as routers?

Yes. Most modern Ethernet switches are capable of handling both types of data-forwarding tasks in a network environment. However, by design, routers are better suited to managing a high volume of data traffic quickly and efficiently. 

What is Power over Ethernet (PoE)?

PoE refers to the ability to provide low-voltage (<100W), DC electrical power to network devices via the same, twisted-pair copper Ethernet cables used to transmit data. This eliminates the need for a separate AC power source, allowing for more flexible placement options without concern for proximity to a power outlet or the need to implement an AC electrical infrastructure. Examples of devices that use PoE include LED lighting, window shades, monitors, sensors, wireless access points, and voice over IP (VoIP) phones.   

PoE is a simple technology, and it’s not new. It’s a low-cost, reliable, and flexible approach to powering smart devices in a network and is crucial to enabling smart buildings and their ecosystems of network-connected devices such as window shades, lighting, thermostats, and security systems.

What are IEEE 802.3af, IEEE 802.3at, and IEEE 802.3bt standards?

As part of the IEEE 802.3 standards that define Ethernet, the 802.3af, 802.3at, and 802.3bt standards define common techniques used to transmit power over copper Ethernet cables (PoE). 

The IEEE PoE standards have significantly evolved since the initial IEEE 802.3af standard that defined up to 15.4W of DC power. This was later superseded by the IEEE 802.3at standard, increasing power up to 25.5 W.

The latest standard, IEEE 802.3bt, was published in 2019 and allows for significantly more power. Currently, up to 100W of power is available to deliver high-speed connectivity over LAN connections and enable many new applications.