What is a Router & Its Functions?

Welcome to the Network Engineer training tutorials by CoreNetworkZ Tech Solutions. Today, I will explain the network device router and its primary functions.

After completing this tutorial, you will learn the definition, functions, and different types of routers.

Let me start the tutorial by explaining the definition of a router. CoreNetworkZ Tech Solutions defines a router as an intelligent network device that connects multiple network devices and communicates between them.

Now, I will explain each term of this standard definition. First, I will explain why I used the term 'intelligent device' in the definition.

A router is an intelligent layer three networking device. It can read and analyze the IP packets sent by other network devices. So it does not blindly forward packets. I hope you understand the reason why it is called an intelligent device.

Do you wonder how a router forwards IP packets? It does it with the help of a routing table and routing protocols.

I will explain it in the next section of this tutorial.

Now, I will explain the second part of the router definition. A router is a layer three device used to connect different networks. It also connects networks with different network addresses.

The router works in the Network Layer (OSI Reference Model) and connects similar and different types of networks.

We need a router to communicate between one FDDI and another Ethernet network.

Ashish Mudgal insisted on including the routing table in this tutorial. My regular readers know him. Ashish is a senior network engineer at CoreNetworkZ Tech Solutions.

So, let me start this section by explaining the relation between a router and the routing table. A router makes routing decisions based on its routing table.

Sarah Brodrecht asked how the routing table helps a router. She asked this question in the comment section. So, I will answer her question here.

A router finds the shortest path to send packets to the destination by calculating the entries in the routing table with the routing protocol.

Carol Allison asked in the comments about the role of Routing protocols in today's router models. Her question requires a detailed article that I will write soon. So, I suggest she read my previous articles on popular routing protocols. The links are below.

1. Interior Gateway Routing Protocol (IGRP)
   
   
2. Routing Information Protocol (RIP)
   
   
3. Address Resolution Protocol (ARP)
   
   
4. Internet Control Message Protocol (ICMP)
   
   
5. Dynamic Host Configuration Protocol (DHCP)
   

You have learned about routers and routing tables. Now, let us check the router functions.

We cannot finish an article about routers without mentioning their functions. The primary functions of a router are:

1. Router Connects Different Network Types.
   
   
2. It joins networks with different network addresses.
   
   
3. It finds the shortest path to send packets to the destination.
   
   
4. It defines logical address schemes.
   
   
5. The router supports VLANs.
   
   
6. The router has features like Quality of Service and Filtering.
   
   
7. It builds routing tables to make layer three decisions fast.

Let us check different types of routers.

Nirupama Rao asked me about different kinds of routers. According to Cisco's guidelines, we can classify routers into five categories. They are:

1. Core router

2. Edge router

3. Distribution router

4. Wireless router

5. Virtual router

Here we provide links to some of our popular configuration and troubleshooting guides.

1. How to Configure Belkin Wireless Device By Manual Steps
   
   
2. Configure D-Link DIR-865L Amplifi Cloud  5700 With Cable & DSL
   
   
3. How to Setup D-Link Wireless
   
   
4. Setup D-Link WiFi WBR-2310
   
   
5. How to Configure Linksys E4200 Wireless-N
   
   
6. Manual Steps to Setup Any Model Of Linksys Routers

You can find some of our recent tutorials below.

Since I have explained the router definition and functions already, let me conclude this article. If anyone is looking for more details, I suggest the following references.

1. https://www.cisco.com/c/en/us/solutions/small-business/resource-center/networking/what-is-a-router.html
2. https://www.systosys.com/viewtopic.php?t=107
3. https://www.juniper.net/us/en/research-topics/what-is-a-router.html
4. https://www.hp.com/us-en/shop/tech-takes/modem-vs-router