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What is a router? What does the router do on the network?

What is a router?

A router (router) is a network device that forwards packets between computer networks. Understandably, routers perform “directing traffic” on the Internet. Data is sent on the Internet as a package, for example, a web page or an email. Data packets will be forwarded from one router to another through small networks, connected together to form an interconnected network, until the packet reaches the destination. How the packet transfer process works, how the packet is delivered to the correct “address” you read will be explored further in the Router Routing section of the Router.

There are many types of routers, from simple to complex. Routers are often used for home Internet connection, and many routers have terrible prices, usually business routers, used in businesses and large organizations. But whether it’s expensive or cheap, simple or complex, every router operates with the same basic principles.

Here, we will focus on the common router, familiar to everyone, if you want to know more about business routers, you can scroll down to the end of the article.

Learn about the router

  • The function of the router
  • Image of Router
  • Router routing process
  • Differentiate router and modem
  • What is the router used for? When do you need a router?
  • Differences between wired and wireless routers

The function of the router

Put simply, A router connects devices in a network by transferring data packets between them. This data can be sent between devices or from device to the Internet. Routers do this by assigning local IP addresses to each device on the network. This ensures data packets arrive in the right place and are not lost in the network.

Imagine this data as a courier package, it needs a delivery address to be able to send to the right recipient. The local computer network is like a suburban road, knowing only the location of the street name without knowing the specific house number in the big world (ie the World Wide Web) is not enough.

This package may be sent to the wrong address with limited information. Therefore, the router ensures that each location (device) has a unique number so that the packet is sent to the correct location. If you need to return the data to the sender or send your own packet, the router does the same. Although it processes each packet individually, it does this very quickly, even if multiple devices are sending data at the same time.

Image of Router

For a better picture, you can see the illustration in Figures A and B. Figure A is the front of a TP-Link Archer C7 AC1750 broadband router, while Figure B is the back of it.

The front of the Router
Picture A: The front of the TP-Link Archer C7 AC1750 router

The back of the router
Figure B: The back of the TP-Link Archer C7 AC1750 router includes a set of ports
RJ-45 is like a hub or switch

Figure A is the front of the router, including beacons, from left to right: power light, wifi beacon (2.4GHz), wifi beacon (5GHz), 4 Ethernet beacons, internet beacon, system beacon .

If you look at Figure B, you’ll see that there are three sets of ports on the back of the router. The left port is where the power source is connected to the router. Blue RJ-45 port to plug the network cable from cable modem or DSL modem.

4 yellow RJ-45 ports are used to plug the network cable to computers in the network, thereby providing a network connection for them.

Router routing process

To understand how routing works, you must first know a little bit about how the TCP / IP protocol works.

Every device connected to the TCP / IP network has a unique IP address limited to its network interface. An IP address is a sequence of four separate numbers separated by dots. For example, a typical IP address looks like:

The most understandable example when talking about IP is the home address. Regular home addresses always include house numbers and street names. The house number specifies the location of the house on that street. IP addresses work the same way. It includes network address codes and device codes. Compared to your home address, you’ll see that the network address is the same as the street name and the device number is the same as the home number. The network address refers to the specific network the device is participating in, and the device number provides the device with an identification on the network.

So where is the end of the network address and the beginning of the device code? This is the job of a subnet mask. The subnet mask will “tell” the computer the last location of the network address and the first position of the device number in the IP address. Subnet activities can sometimes be very complex. You can refer to it in more detail in another article that we will introduce later. Now for the simplest things, consider a very basic subnet mask.

The subnet mask at first glance is very similar to the IP address because it also has 4 numbers formatted in a style separated by dots. A typical subnet mask looks like:

In this particular example, the first three numbers (called octets) are all 255, the final number is 0. The number 255 indicates that all the bits in the corresponding location of the IP address are part of the code. fate. The last zero indicates that no bit in the corresponding location of the IP address is part of the network address. Therefore they belong to device codes.

It sounds quite confusing, you will understand more with the following example. Imagine you have a computer with an IP address of and a subnet mask of: In this case, the first three octets of the subnet mask are all 255. This means that the first three octets of the IP address belong to the network code. Therefore the network code location of this IP address is 192.168.1.x.

This is important because the router’s job is to transfer data packets from one network to another. All devices in the network (or specifically on the network segment) share a common network number. For example, if 192.168.1.x is the network number associated with the computers connected to the router in Figure B, the IP addresses for the four tablets might be:


As you can see, each computer on the local network shares the same network address, and the device code is different. When a computer needs to communicate with another computer, it does so by referring to that computer’s IP address. For example, in this particular case, a computer with an address of can easily send data packets to a computer with an address of because both machines are part of the same physical network. physical.

If a machine needs to access a machine on another network, things are a bit different. Assume that one of the users on the local network wants to visit the website quantrimang.com, a website located on a server. Like any other computer, every Web server has a unique IP address. The IP address for this website is

You can easily see that the website’s IP address is not on the 192.168.1.x network. In this case, the computer that is trying to reach the website cannot send the data packet over the local network, because the Web server is not part of the local network. Instead, the computer that needs to send the packet will consider the default gateway address.

The default gateway is a part of TCP / IP configuration in a computer. It is a basic way to tell the computer that if you do not know where the packet is sent, send it to the specified default gateway address. The address of the default gateway is the IP address of a router. In this case, the router’s IP address is selected as

Note that the router’s IP address shares the same network address as other computers on the local network. This is so it can access computers on the same network. Each router has at least two IP addresses. One uses the same local network network address, and the other is determined by your ISP. This IP address uses the same ISP network address. The job of the router then is to transfer data packets from the local network to the ISP network. Your ISP has its own routers that work just like any other router, but route data packets to other parts of the Internet.

When do you need a router?

Technically, if you only want to connect to the Internet for one device, you only need to use a modem. Although for security and flexibility, it’s best to use the router even if there is only one device on your network.

But when it comes to providing Internet for devices such as mobile phones and smart TVs, routers are indispensable devices. Remember the example of street name and house number. If there is only one house on a road, you do not need the house number because it has only one location. But when there are many houses on that road, you need a specific address.

Users need routers not only to connect to multiple network devices but also to connect multiple devices. Without the Internet, you can still create a local area network of computers and other devices. This allows you to transfer and share files with specific devices on a network such as printers, scanners and game consoles.

  • Transfer data between computers

The router connects multiple devices

Without a router, data will not be sent to the right device. The document print job becomes useless when it is sent to a smartphone or Google Home speaker instead of the printer.

Speaking of Google Home, routers are even more necessary if you need to connect to a Smart home. Because the Smart home is also a local area network of devices, without a router they cannot communicate with each other. You can still use the local network without an Internet or modem but can’t without a router.

Differences between wired and wireless routers

The difference between a wired router and a wireless router is the type of connection each device uses. Wired routers only have LAN cable ports, while wireless routers (also known as Wifi routers) have wireless antennas and adapters that allow devices to connect without cables. Most routers and modems today have LAN ports and antennas. There are a few things you need to remember when choosing a Wifi router to make sure you choose the right one.

As you can see, routers are extremely important network components. Without routers, interconnection between networks (such as the Internet) is not possible.

What’s the business router so expensive?

Let’s take a look at the basic functions of a router used in large enterprises and organizations. Below you will understand why:

  • Business routers often take the form of a device with more services, for example, in addition to providing network services, applications and security.
  • Integrated hardware-based VPN for remote access customers and employees.
  • Highly configurable, offering advanced options for managing connected devices, such as quality of service (QoS) control for specific devices, ports and types of traffic.
  • High-end business routers, such as those developed by Cisco, will require separate devices to create wireless access points and will use external switches to connect wired devices to routers.
  • Business routers often use high quality components, which work well continuously for many years.

As you can see, the business router is more complex, it also omits some features that home routers have. Business routers are designed to be the only high-performance device in a larger and more complex network, while home routers are designed to be an all-in-one, easy to connect and access solution. .

See more:

  • Differentiate Modem and Router
  • Reboot the router and modem properly?
  • Why should you restart your router regularly?
  • These “great way” to accelerate Wifi for Wireless Router


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