A local-area network (LAN) connects devices within a limited physical area. Devices on a LAN will typically be connected with wires conforming to IEEE Ethernet specifications or wirelessly using WiFi which conforms to IEEE 802.11 standards.
Small LANs for personal use or for a small organisation may consist of
Endpoints – computers, printers, phones, tablets and more.
A wireless access point.
A network switch with 4 – 8 ethernet ports.
A network router.
Some endpoints will connect directly to the switch using Ethernet cables and others will connect to the wireless access point (WAP) using WiFi. The WAP is then connected to the switch.
The switch connects to the router which is connected to the Internet via an Internet Service Provider.
In reality, the Wireless Access Point, switch and router will often be integrated into a single device (which is often marketed as a ‘router’).
For larger organisations, the devices which make up a network will perform the same functions but on a larger scale to support many more endpoints. For example and organisation might have
One switch for each floor (each with 24 or 48 Ethernet ports)
One wireless access point connected to each switch
An additional switch to aggregate connections from each floor
A separate router which is connected to the Internet or the organisation’s Wide Area Network (WAN).
Connections and cables will still use standards from the Ethernet and WiFi (802.11) families.
A network switch is typically a device which operates at layer 2 of the OSI model. It is concerned with sending and receiving Ethernet frames within a LAN.
A network router is a layer 3 device. It operates at the Internet layer of the TCP/IP model and therefore understands the Internet Protocol (IP) and is able to route packets based on IP addresses.