Transmission Media (OSI Layer 1 Physical)
The transmission media refers to the physical pathways that connect computers, other devices, and people on a network. It includes copper wires, fiber-optic cables, and wireless radio frequencies that transmit data as electrical, light, or radio wave signals.
Router (OSI Layer 3 Internet)
A router is a device that connects multiple networks and forwards data packets between them. Operating primarily at the Internet Layer of the TCP/IP model, routers utilise IP addresses to make decisions about the most efficient path for sending packets to their destination across diverse networks, managing traffic and handling congestion.
Gateway (OSI Layer 3 Internet)
A gateway serves as a network point that acts as an entrance to another network. In the context of TCP/IP, it is often used to mean a device that routes traffic from a local network to the internet – a function similar to a router. However, gateways can also operate at higher layers for protocol translations or connecting radically different systems, such as translating between different communication protocols or interfacing different operating systems.
Switch (OSI Layer 2 Datalink)
Switches operate at the Network Layer and are used to connect devices within the same network (LAN). They use MAC addresses to forward data frames to the correct destination within the network, reducing collisions and improving network efficiency by segmenting data traffic.
Wireless Access Point (WAP) (OSI Layer 2 Datalink)
A wireless access point enables wireless devices to connect to a wired network using WiFi (802.11). It acts as a central transmitter and receiver of wireless radio signals. It functions at the Network Layer.
Firewalls (OSI Layer 3, but can be layer 2)
Firewalls are security devices that monitor incoming and outgoing network traffic and decide whether to allow or block specific traffic based on predetermined security rules. Firewalls can operate at different layers of the TCP/IP model, from the Network Layer up to the Application Layer. They can filter traffic based on IP address and port (network and transport layers) or inspect the content of communications (application layer) to identify and block malicious traffic, such as viruses or hackers.