How Does a Network Work

 

 

Overview 

Networks are something that we use in our everyday lives, but may not frequently think about how they actually work.  What happens when you connect to Wi-Fi?  What is the path data takes to get from your computer to a recipient across the world?  We will explore the basics of network connections here.

Types of Networks 

There are a few different levels of computer networks.  A Personal Area Network (PAN) is the smallest version, consisting of one person and a few devices, maybe a laptop and printer, or your cell phone and your Bluetooth headphones.  In your office you may have a Local Area Network (LAN), connecting everyone’s computer, printers, scanners, to a single shared internet connection.  If you go to a coffee shop and type in a password to get on their Wi-Fi to do your freelancing work, you are connecting to their LAN.  LANs may have their own rules set up.  A company or school may restrict certain websites from being accessed from their network, for example.  Larger networks exist by connecting smaller networks.  The largest of which is the internet, which covers almost the entire world.  When multiple LANs are connected together the result is called a Wide Area Network (WAN).   The global internet is made up of many WANs and LANs all connected together. 

How Computers Connect in a Network  

Like electrical circuits, the design of the connection patterns of networks matter.  A network’s design or architecture is called the topology.  Historically, there have three common ways the client computers and devices in a network could be connected: in a line, a ring, or a star topology.   

 

Network Device Roles 

The permissions of communication between devices on a network is of specific interest to cybersecurity professionals, and will be discussed in detail in a future post. 

The devices on a network can have one of two roles, either a client or a server.  A client requests and uses data.  Common devices that function as clients are computers, cell phones, tablets, and printers.  Servers sometimes store data that is used by the consuming clients.  Some servers run applications or programs for the clients they serve.  And some servers do both, run applications and provide data for clients.  Servers typically have a large capacity for storage and memory, and very high processing abilities.  There are usually many more clients than servers in a given network.  Sometimes a device can serve as both the client and the server, requesting data from one source while providing it to another.  This interaction is called peer-to-peer networking.  

Network Cards and Connectivity 

Network-ready devices come with a network card installed, that tells a network how to interact with the device.  Each network card has a number associated with it called the Media Access Control (MAC) code or MAC address. This code allows the network to uniquely identify devices.  You can think of MAC addresses being used to identify devices on a network in the same manner that Social Security numbers or federal ID numbers are used to identify people uniquely.  Network permissions can be put in place to allow only certain MAC addresses on the network.  This can play an important role in cybersecurity of networks, though it is not completely reliable, since just as Social Security numbers can be stolen and used illicitly, MAC addresses can be cloned and used illicitly.  

Networking Devices: Hubs, Switches and Routers 

There are a pieces of networking hardware required to make the required connections between devices.   

A network hub is essentially a box that you can plug more than one computer, or client, into that allows them to communicate with each other.  Hubs are part of the physical layer (Layer 1) of the Open Systems Interconnection (OSI) model.  There are three main types of hubs: 

  • Passive –  transmits the packets electrical signal as-is 
  • Active –  amplifies the electrical signal before transmitting it 
  • Intelligent –  allows for remote management of network support 

Similar to network hubs, network switches connect multiple clients so they can communicate.  The main difference here is that network hubs cannot actually inspect the packets of information being transferred.  The switch can read data and decide where to send it based on the desired destination, whereas a hub sends the data everywhere.  This helps conserve bandwidth and improves performance.   

In addition, there are network routers, which you have probably heard of and could find in your own home.  Routers work to connect two networks together, beyond just connecting multiple computers.  A router functions in Layer 3 of the OSI model, at the network layer.  Routers can filter both incoming and outgoing network traffic.  Routers keep packets of data within a network segment and prevent some of those packets from crossing over from a LAN to the other side, or WAN side, of the router.  This helps to make networks more efficient and can provide some security as well. 

Home networks typically connect to the internet through Internet Protocol (IP) using a router to communicate with a WAN provided by the Internet Service Provider or ISP.  The router is what connects devices in your home to the internet through wired Cat-5 and Cat-6 connections or wirelessly through Wi-Fi within your home. On the WAN side of the router a broadband connection is made to the ISP through a fiber cable, coax cable, or other high-speed connection.   

For more details on the specifics of various types of routers, check out https://www.lifewire.com/how-routers-work-816456 

Conclusion 

Together, these pieces of hardware are linked to make the network.  The idea of the internet becomes less intangible when thought of as the hardware that makes it up.