Network devices, functions, and topologies

Network device functions

An endpoint is a device using the network, such as a laptop. A server provides a service. A switch forwards local Ethernet frames; a router forwards IP packets between networks. A Layer 3 switch can do both. An access point connects wireless devices to a network. A controller manages supported devices centrally.

A firewall applies traffic policy. An intrusion prevention system inspects traffic for signs of attacks and can block matching traffic. These tools do not make a network automatically safe. Power over Ethernet (PoE) carries electrical power on supported Ethernet links, often for phones and access points.

Network architecture and topology types

A small-office network device may combine routing, switching, wireless access, and firewall functions. In a larger campus, access switches connect users, distribution devices combine access networks, and a core moves traffic between major areas. A two-tier design combines distribution and core duties. A three-tier design separates them.

A spine-leaf design connects each leaf to the spines to provide predictable paths, commonly in data centres. A wide area network (WAN) joins distant sites. Cloud networking uses virtual networks and services hosted by a provider; it still needs addressing, routing and access rules. A diagram shows relationships, not necessarily the physical distance between devices.