A Free Educational Resource Created by Carnegie Mellon University to Empower You to Secure Your Part of Cyberspace

Router

A computer networking device that forwards data between networks

A router is a device that is connected to multiple networks. Each network may be of a different type. The purpose of a router is to transfer data from one network to another. A router can also be used to transfer data within the same network.

A router forwards data packets from one device to another. The data that arrives into the router from a device is examined and the destination of the packet is found. Based on this destination, the router sends the packet on the appropriate output line. If a router is not able to determine how to direct the packet, it may send the packet to another router that is adjacent to it. A data packet may traverse several routers before it reaches the destination.

Routers come with different capacities based on the areas in which they are used. The capacity is normally specified by the number of devices that can connect to it or the maximum data that the router can handle at a given period of time. A small router capable of handling around five to 10 devices is normally used in a home network or a very small office. Larger routers are used in offices or universities. There are also routers that are used to direct traffic between cities, countries and even continents.

Working of a Router

Imagine that you are visiting a theme park and are interested in a few rides. You may ask any employee of the theme park for directions. The person will guide (route) you by giving you directions. The employee of the park will, in effect, act as a router who will direct incoming people to the destination of their choice.

To reach a destination a data packet will usually go through multiple routers. Consider that you have come across an advertisement about a particular brand of television in a store at a mall. When you visit the mall, you may ask the mall attendant for directions to the store. The attendant will guide you to the entrance of the store. From there on, a store employee will direct you to the electonics department. From thereon, another employee may direct you into the television section. In this way, multiple people have routed you to the intended destination.

How Routers Are Used in Various Networks

Home Network

In a home, a router is normally used to share the Internet connection between multiple computers at home. The same router can also be used to share data between the computers. When you enter a website address in a browser, the home router will send the request on the Internet connection. When you request data from another computer connected to the router, the router will send the request directly to the other computer without using the Internet.

Office or University Network

A university will typically have multiple routers connecting various computers. There may be a router for each building of the university. These routers may be, in turn, connected by other routers. When data is requested from an internal website, the request is routed through internal networks. When the request is for an external website, the request is sent through a router connected to the Internet.

Configuration of a Router

A router can be configured with various settings before it can be used. Configuring a home router is very easy as the main purpose is to connect to the Internet. Configuring a commercial router to be used in corporations and large networks is more complex. The following webpages outline the steps needed to set up a home network and an office network using a router:

Options for Setting Up a Router

A router can perform much more than just directing traffic from input to correct output path. The following list includes some of the features of a modern router:

  • Controlling the amount of traffic that flows into a particular network
  • Limiting the types of traffic that can flow into and out of the router (a kind of firewall)
  • Enabling priorities for important traffic
  • Automatic recovery from any errors
  • Automatic learning of new networks which are connected to the router

Legal Issues

Legal

If you own a router, you must ensure that it is maintained securely. If any malicious entity misuses your network, then you may be held responsible for the consequences. Also, for the same reason, you must be careful in sharing Internet connections with others. Most people share a single Internet connection by the use of a router. You should do this only with highly trusted people. You should ensure that the router is secured with strong passwords and highest levels of available encryption. This will reduce the chances of hackers getting access to your router.

References

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