What is a router?


A router is a device that connects two or more computer networks and allows data packets to be routed between different machines in a network according to well-defined rules.


A router allows you to leave your local network, which comprises computers are at home, for example, and to go on the global network that is the Internet.


Discover in this article how a router works and how to categorize them.


How a router works.


A router connects to an Internet Service Provider (ISP) such as Free, SFR, Orange, … via its DTE connection port. It is a serial port intended for the WAN connection, i.e. the connection with the Internet service provider. It is the latter (FAI) that will take care of routing the outgoing information from your computer, for example, on the Internet and input and output.


In a local network such as a home network, for example, a router assigns an IP address to a machine on that network (when DHCP is enabled) and also serves as a gateway gate or opening allowing any machine on this network to send data packets or information on the internet or to receive any.


The mechanism of routing data from one machine to another is governed by a rule or protocol. There are several protocols each with its specification.


Here are some protocols implemented on the routers:





The RIP protocol.


The principle of the RIP protocol is very simple. For a router to send information from one router to another, if there are multiple routes, the RIP protocol will choose the shortest route.


There are two variants of RIP. We have RIP v1 and RIP v2. The two versions differ in their way of sending the information in relation to the paths or routes (links), in the sense that for the first version, the sending is done in Broadcast sending the data to all machines on a network, while in the second version, it is done in Multicast which comprises sending the data to a well-defined group of computers on a network.


The BGP protocol.


This is the Internet protocol ISP uses that. It allows the communication of different networks.

Router types.


Routers are categorized into three groups:


Basic or wired routers.


Being in the form of boxes connecting to computers via cables, they also have ports allowing them to connect to the modem to receive data packets from the Internet. They can connect two or more networks according to their number of ports (network interface). We can categorize them into two groups:


The routers “core”.


The most powerful and the fastest, we find them in internet providers. They allow the transfer of information via the main backbones (large links) of submarine optical fibers that connect the continents.

Access routers.


They are less powerful and slower than the first, connect more or less medium-sized business networks.


Wireless routers (Wi-Fi router).


Similar to wired routers, wireless routers instead of using cables to distribute data packets from one PC to another in a network, instead use antennas. The data packets are converted to radio signals or waves and then directed by the antennas to the specified computer or machine.


4G routers.


The 4G router (or LTE router) is an electronic device that makes it possible to provide an Internet connection based on a 5G, 4G or 3G mobile network for individual or collective use. It is this type of routers that are embedded in mobile phones and so you can share the connection with your surroundings.


Internal components of a router.


A router has about the same components as a real computer, although it is designed to perform a very specific function other than that of a conventional computer.


It has a processor, memory, data bus and input, and output units. It even has an operating system (example: Cisco IOS) that allows you to run the configuration files.


Central unit.


The latter executes the instructions of the operating system which is nothing other than the operating system of a router just as Windows is for a computer and Android for a mobile phone.





Flash memory.


It is used to store a complete image of the software platform (operating system) that can be compressed for space requirements because this memory is very small.




This is the memory that contains the instructions when the router is running, that is, this memory is active when your router is turned on. Once this is off, the RAM is empty and the startup instructions and configuration files are stored in the NVRAM which allows itself to store the configuration of the router when it is off.


The interfaces or connection ports.


They connect the router to the local network for the input and output of packets.




It keeps the instructions of the automatic start test. This memory is used when you want to configure your router for the first time or when you want to reconfigure it after you reset it completely.


External components of a router.


They essentially consist of connection ports. There are several to know:

LAN ports.


They connect the router to media or LAN cables. They can be of several types to know: Ethernet port, Token Ring or FDDI.

WAN ports.


They allow the router to connect to the internet using the services of the ISP. These are essentially the serial ports, namely the DTE port on the client-side router and the DCE port on the ISP’s router.


Console or Auxiliary ports.


They are management ports for configuring and administering the router from a terminal or just a computer.


How to choose a good router?


Many criteria must be taken into account, for example, the number of ports for local network media, the signal strength when it comes to a wireless router as well as the speed of data transfer. We must also make sure to choose the encryption for increased security.