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Components of a Router

Last Updated : June 9, 2022
components of router

Hey there, if you too, as a kid, used to unscrew all your toys to check what exactly is it made up of? Then this blog is just for you. So today, we will unscrew the most exciting toy for a Network Engineers, i.e. a router and look into all the components of this device. Yes, you guessed it right we are going to learn about the Components of a Router. 

What are the Components of a Router?

components of a router

The components of a router are majorly categorised into: 

1. External Components 

2. Internal Components  

Let's discuss both one by one, starting with the external components of router. 

External Components of Router:

External Components of router include the external ports of the router. These ports are divided into three categories i.e., LAN ports, WAN ports and Admin Ports. 

  1. WAN Port: This is the port wired to the Wide Area Network or to an external network, which is typically the Internet. 
  1. LAN Port: This is the port connected to the Local Area Network or, in simpler words, the port which will be connected to your switch. 
  1. Admin Port: They are used for the administration or configuration of the router with the help of HyperTerminal applications.

These ports are available in a variety of categories:

Ethernet
Fast Ethernet
Gig Ethernet
LAN Port
Serial PortWAN Port
Console Port
Auxiliary Port
Admin Port

These were the external components of a router. Now, let's dig inside the Internal Components of Routers. 

Internal Components of a Router:

  • CPU: What does the CPU used for? Well, it is there for computing, but what else? So, everything you are performing is done with the help of the CPU. The algorithms like Dijkstra or DUAL work with the help of the CPU to get things done right. 
  • ROM (Read Only Memory): It's something similar to the BIOS chip of our computers. It is used to store the Bootstrap program, required for loading the Operating System of the Router. In Cisco devices, the operating system used is called Cisco IOS (Internetwork Operating System). This operating system is stored inside another component of the router called Flash.  
  • Flash: It is used for storing the Operating System 
  • Non-Volatile RAM (NVRAM): This is the permanent memory which can be used for storing the configurations. If you want any configurations or changes made on the router permanent, which means that it should not go away even if we reboot the device. Then, we must save the configuration into NVRAM as Startup-config. 
  • RAM (Random Access Memory): It is the main memory used to store the configurations but temporarily. The temporary configurations are called Running-Config, which can be seen using the command "show running-config". RAM is volatile. If you power off the router, everything you have stored inside the RAM will go away, so make sure you move it to NVRAM by using the command write. 

After learning about all these components of a router, the question comes to mind is, how does this work together to boot up a router? So, let's understand the booting process of router. 

Booting Process of Router

The booting process of router happens in three steps, and it starts with the very first step, performing the POST and loading the bootstrap program. 

  1. The power on self-test is a process that happens mostly on all the computers when they boot up. It is a test to check all the hardware of the device. After the completion of the power-on self-test, the bootstrap program is loaded. This bootstrap program is something includes the iOS and is loaded into the RAM. 
  1. The next step is to locate and load the iOS software; the location of the iOS file is specified by the value of the configuration register setting. The bits inside this file instruct the device to load IOS either from flash or the TFTP server. To load the iOS normally from flash, the configuration registered setting should be set to 0x2102. 
  1. The 3rd step of the booting process of router is about locating and executing the startup configuration if it exists. After booting the iOS, the router looks for the startup-config file inside NVRAM, which you might have saved before shutting the router off. This file contains the configurations, passwords, information or some interface addresses which you might have configured earlier and have saved into the NVRAM as permanent configurations. If a startup configuration file is found, then that is executed. 

This is the booting process of router explained in three steps. This whole topic is a part of our CCNA training.

FAQs on Components of a Router: 

Question – What are the 4 components of a router? 

Answer – The 4 components of a router are: 

  1. Routing processor, which creates a forwarding table used in packet forwarding. 
  1. Input ports are the initial points form where, the packets enter the router. 
  1. The Output ports store the incoming packets and schedules them for service.  
  1. Switching fabric is the interconnection between the input and output ports. 

Question – What are the external components of a router? 

Answer – The external components of a router consist of the external ports of the router and are categorized into 3 categories which are: 

LAN port, WAN port, and Admin port. 

These are the main external components of a router: 

  1. Ethernet 
  1. Fast Ethernet 
  1. Gig Ethernet 
  1. Serial Ports 
  1. Console Port 
  1. Auxiliary Port 

Question – What are the main components of a cisco router? 

Answer – The main components of a Cisco router are: 

  1. CPU 
  1. ROM 
  1. RAM 
  1. NVRAM 
  1. Flash 
  1. Ethernet 
  1. Ports 
  1. IOS 
  1. Interfaces 

Question – Is a router a set of components? 

Answer – Yes, a router is a set of components. There are two types of components present in a router: the internal components and the external components. The internal components of the router are used for data packet transfer while External components are the components that exist on the back on the router. 

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