Components Of a Network

By Kyle Hofberg

1. Router

A router is a device that forwards data packets between computer networks, creating an overlay internetwork. The most familiar type of routers are home and small office routers that simply pass data, such as web pages, email, IM, and videos between the home computers and the Internet. An example of a router would be the owner's cable or DSL modem, which connects to the Internet through an ISP.

A Cisco ASM/2-32EM router deployed at CERN in 1987.

2. SWITCH

A network switch is a computer networking device that links network segments or network devices and a switch can also be explained as a telecommunication device that receives a message from any device connected to it and then transmits the message only to the device for which the message was meant. This makes the switch a more intelligent device than a hub (which receives a message and then transmits it to all the other devices on its network).

Avaya ERS 2550T-PWR 50-port network switch.

3. Hub

An Ethernet hub, active hub, network hub, repeater hub, multiport repeater or hub is a device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer of the OSI model. The device is a form of multiport repeater. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision.

4-port Ethernet hub.

4. Server

In most common use, a server is a physical computer (a computer hardware system) dedicated to run one or more services (as a host), to serve the needs of the users of other computers on a network. Depending on the computing service that it offers it could be a database server, file server, mail server, print server, web server, gaming server, or some other kind of server.

Servers in a data center. Several servers are mounted on a rack and connected to a KVM switch.

5. Client

A client is a computer program that, as part of its operation, relies on sending a request to another computer program (which may or may not be located on another computer). The term "client", however, may also be applied to computers or devices that run the client software or users that use the client software. For example, web browsers are clients that connect to web servers and retrieve web pages for display. Email clients retrieve email from mail servers. Online chat uses a variety of clients, which vary depending on the chat protocol being used. Multiplayer video games or online video games may run as a client on each computer.

6. NIC

The NIC allows computers to communicate over a computer network. It is both an OSI layer 1 (physical layer) and layer 2 (data link layer) device, as it provides physical access to a networking medium and provides a low-level addressing system through the use of MAC addresses. It allows users to connect to each other either by using cables or wirelessly.

A 1990s Ethernet network interface controller card which connects to the motherboard via the now-obsolete ISA bus.