Introduction to a Router

Network devices are physical devices that enable the hardware of a computer network to communicate and interact with each other. For example, repeater, hub, bridge, switch, router, gateway, router and NIC etc.

What is a Router?

A router is a network device that forwards data packets between computer networks. One or more packet-switched networks or subnetworks can be connected via a router .By sending data packets to the designated IP addresses, it manages data traffic between different networks and allows multiple devices to share an Internet connection. Let’s understand this with a very general example: Suppose you search for in your web browser. Then this will be a request sent from your system to the Google server to serve this web page, so your request Nothing more than a stream of packets that not only goes to the Google server immediately, but also a series of network devices, a so-called router, which accepts these packets, forwards them to the correct path and thus reaches the Google server. Goal.  A router has multiple interfaces that allow it to connect to multiple host systems. Routers are the devices that work at the network layer of the OSI model; These are the most commonly used devices in networks.

How does the router work?

  • A router determines the future path of a packet by examining the destination IP address in the header and comparing it with the routing database. The routing table list describes how data is sent to a specific network location. They use a series of rules to determine the most effective way to transfer data to the specified IP address.•
  • To enable communication between other devices and the Internet, routers use a modem, such as a cable, fiber optic, or DSL modem. Most routers have many ports that allow a variety of devices to be connected to the Internet at the same time. Routing tables are needed to decide where the data is delivered and where the traffic comes from.
  • A routing table primarily specifies the router’s default route. Therefore, the optimal data forwarding path for a particular packet may not be determined. For example, your office router routes all networks to your ISP via a single standard channel.
  • Static and dynamic tables are available in two versions in the router. Dynamic routers automatically update dynamic routing tables based on network activity, while static routing tables are configured manually.

Router Types

There are different types of routers. Some of them are listed below:

  1. Broadband Routers – These are one of the most important types of routers. It is used to make different types of things. It is used to connect computers or to connect to the Internet.
  • Wi-Fi Routers: These routers are used to generate a Wi-Fi signal in your office or home.
  • Wired Router: A wired router is used to connect multiple wired devices using an Ethernet cable. It takes the data transmitted from the modem and distributes it to another network. It is widely used in schools and small offices.
  • Edge Routers: As the name suggests, they are located at both ends, usually connected to an Internet Service Provider, and distribute packets across multiple plans.
  • Core Router : Core router distributes packets within the same network. The main task is to perform large data transfers.
  • Virtual Routers: They are implemented by software on virtual machines and are more flexible and scalable.

Portable Routers: This router is used to create personal Wi-Fi and hence designed for easy portability.

Functions of Router 

Router performs below main functions:

  1. Forwarding: Router receives packets from its input ports, checks its headers, performs several functions as basic as verifying the checksum and then consulting the routing table to find the correct output port. to dump packets and forward packets to that output port.
  • Routing: Routing is the process by which a router determines what is the best path for a packet to reach its destination. It maintains a routing table created using different algorithms only by the router.
  • Network address translation (NAT): Routers use NAT to translate between different IP address ranges. This allows devices on a private network to access the Internet using a single public IP address.
  • Security: Routers can be configured with firewalls and other security features to protect the network from unauthorized access, malware, and other threats.
  • Quality of Service (QoS): Routers can prioritize network traffic based on the type of data being transmitted. This ensures that critical applications and services receive sufficient bandwidth and are not impacted by lower priority traffic.
  • Virtual Private Network (VPN) Connection: The router can be configured to allow remote users to securely connect to the network using a VPN.
  • Bandwidth management: Routers can be used to manage network bandwidth by controlling the amount of data allowed to flow across the network. This can prevent network congestion and ensure that important applications and services receive enough bandwidth.
  • Monitoring and Diagnostics: The router can be configured to monitor network traffic and provide diagnostic information in the event of network outages or other problems. This allows network administrators to quickly identify and resolve problems.

Router Architecture

A generic router consists of the following components: 

  1. Gateway: This is the interface through which packets are received into the router, it performs some key functions such as connection termination physical connection to the router level, which is done through the leftmost port. in the diagram below and the middle section implements decoding-like link layer interoperability, at the input port end the forwarding table is looked up and used to determine the appropriate output port
    depending on the destination address.
  • Switching Fabric: This is the heart of the router, it connects input ports with output ports. It is a type of network inside a network device. The switching architecture can be implemented in many ways, some of the most important ways are:
    • Memory switching: We have a processor that copies the packet from the input ports and sends it to the output port out appropriately. It operates like a traditional processor with input and output ports serving as input and output devices.
  • Bus switching: In this implementation, we have a bus that connects all the input ports to all the output ports. When the receives a packet and determines which output port it should go to, the input port places a specific token on the packet and passes it onto the bus.All output ports can see the packets but they will be sent to the output port with the token inserted, the token will then be discarded by that output port and the packet forwarded
  • Switch via connection network: this is a more complex network, here instead of a single bus, we use a 2N bus to connect n input ports with n output ports.

Output port: This is the segment where packets are transmitted out of the router. The output port checks its queue buffer (when multiple packets need to be transmitted through the same output port, a queue buffer is formed) and receives the packets, performing link layer functions and finally jointly transmit packets to an outgoing link.

Routing Processor: It implements routing protocols and works like a traditional processor. It uses different routing algorithms such as link state algorithm, distance vector algorithm, etc. to prepare the forwarding table, consulted to determine the route and exit gate.

Architecture of Router

Security Challenges in Routers

Routers face a number of challenges due to unauthorized access by another party. Here are some router security challenges.

1.   Exploiting Vulnerability

Firmware is automatically installed on all hardware routers to support router operations.Like any other program, router firmware often has vulnerabilities that hackers can use against it. Router vendors often release updates to fix these errors. Therefore, the router’s firmware needs to be updated regularly. Attackers have the ability to monitor traffic on unpatched routers and use them as part of a botnet.

2.   DDoS Attacks

Distributed denial of service (DDoS) attacks against network infrastructure typically target organizations large and small.Network outages can be caused by unresolved DDoS attacks at the network layer, which can overload routers or cause them to stop working. Using Cloudflare Magic Transit is one way to protect your network and routers against these types of DDoS attacks.


3. Administrative Credentials

To perform administrative tasks, a set of administrator credentials is included in each router. The default value for these logins is “admin” for username and “admin” for password. As soon as possible, change your username and password to something more secure because, If not modified, an attacker could use them to take control of the router remotely. They know the typical default values ​​for these credentials.

Advantages of Router


  • Easier connection: Sharing a single network connection between multiple machines is the main advantage of the router. This allows more people to connect to the Internet, thus increasing overall productivity. Additionally, routers have connections between different network designs and media.
  • Security: Undoubtedly, installing a router is the first step in securing a network connection. Because using a modem to connect directly to the internet exposes your computer to several security risks. So that the environment is somewhat secure, routers can be utilized as an intermediary between two networks. While not a firewall or antivirus replacement.
  • NAT Usage: Routers use Network Address Translation (NAT) to map multiple private IP addresses into one public IP address. This allows for better Internet connectivity and better information flow between all devices connected to the network.
  • Dynamic Routing Support: The router uses a dynamic routing strategy to support network communication. The optimal path of the Internet job is selected using dynamic routing. In addition, it also creates collision and diffusion domains. Overall, this can reduce network traffic.

Packet filtering: Packet switching and packet filtering are two other services of a router. A set of filtering rules used by routers to filter the network. Packets are allowed or forwarded.



Disadvantages of Router


  • Slower: Router analyzes many layers of information, from physical layer to network layer, slowing down the connection. The same problem can also occur when multiple devices are connected to these network devices, causing a “connection waiting” condition.
  • High cost: They are more expensive than some other system administration tools. This includes safety, access and contacts. So, routers are generally not the best solution when problems arise.
  • Configuration requirements: The router must be configured properly to operate properly. In general, the more complex the intended use, the more configuration is required. This requires professional installation, which can increase the cost of purchasing the router.

  • Quality issue: Time conversion is not always accurate. However, some modern devices use the 2.4 GHz band, which is often disabled. These types of separations can often occur for people living in apartments and condos.
  • Lack of bandwidth: Dynamic routing techniques used by routers to support connectivity tend to overload the network, consuming a lot of bandwidth. This causes a lack of bandwidth, significantly slowing down the Internet connection between connected devices.


Applications of Routers


There are several applications of routers because today routers are widely used in most communication networks for better communication:

  • Hardware devices such as BSC servers , MGW, IN, SGSN and other remote networks are connected to these networks through routers.
  • It is used in wired and wireless communications because it supports high data transmission rates through the use of STM. connect to connect
  • Routers are often used by Internet service providers to transmit data such as audio, video, images, and email from one location to another. Additionally, it can transmit data globally using the destination’s IP address.
  • Router provides access control capabilities. It can be configured so that some users can access all of the data while others can only access a subset of that data.

Routing Protocol


The router can recognize other routers in the network and automatically decide where to forward all network messages through the routing protocol. There are several protocols, some of which are listed below:

Shortest path first: When packets move across multiple networks, it is used to determine the optimal path they should take to destination.

Border Gateway Protocol (BGP): It facilitates the sharing of information between border routers to control the routing of Internet packets. As for routers, it brings stability to the network. It can easily switch to another network connection to forward packets.

Internal Gateway Routing Protocol (IGRP): IGRP describes a protocol for exchanging routing data between gateways within separate networks. The routing information can then be used by other network protocols to decide how to route data pack

Enhanced Interior Gateway Routing Protocol (EIGRP): This protocol instructs the router to route its neighbour if it cannot find a path to the destination from the routing tables. The neighbour then forwards the request to another neighbour until the router finds the path.

Exterior Gateway Protocol (EGP): It is also commonly used to communicate routing table data between Internet hosts.

Router Introduction FAQ


Router – FAQs

How is a Router different from Wi-Fi?

A router is not just for Wi-Fi, although it can broadcast a wireless (Wi-Fi) signal to connected and supported devices. In addition, the router provides a wired connection to the Internet. Once the router establishes a wired or Ethernet connection to the Internet, it can convert that connection into a Wi-Fi signal that multiple devices can receive.

What is the difference between a modem and a router?

A modem, commonly known as an ISP, is the device that connects your home network to your Internet service provider. A router is a device that allows all of your wired and wireless devices to access the Internet simultaneously and communicate with each other.


Can a router have two IP addresses?

Your router itself has several IP addresses. In addition to the router’s internal IP address, which serves as the default LAN gateway, it also contains additional private IP addresses for each device and a “management” private IP address.


What is SSID?

SSID stands for “Service Set Identifier”. The SSID allows users to locate and join the wireless network broadcast by the router.


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