What is a Router and How Does it Work? Guide in 2025

What is a router?

A router is a device designed to link two or more packet-switched networks or subnetworks. Its main roles include directing traffic between these networks by routing data packets to their destination IP addresses and enabling multiple devices to access a shared Internet connection.

Routers come in various types, though most typically transfer data between LANs (local area networks) and WANs (wide area networks). A LAN consists of interconnected devices within a limited geographic region, typically managed by a single router.

In contrast, a WAN spans an extensive geographic region. Large organizations or companies operating across multiple locations nationwide will generally need distinct LANs for each site. These LANs then interconnect to form a WAN, requiring multiple routers and switches* due to the broader network distribution.

Types of Router

There are various categories of routers, each serving distinct functions. Below are some of the primary types:

1. Broadband Routers: These routers are essential for connecting multiple devices to the internet or each other. They facilitate various tasks and ensure seamless online access.
2. Wireless Routers: Designed to generate a wireless network, these routers allow devices to connect without physical cables, making them ideal for homes and offices.
3. Wired Routers: These routers connect several wired devices through Ethernet cables. They receive data from a modem and distribute it across a local network, commonly used in educational institutions and small businesses.
4. Edge Routers: Positioned at the network’s perimeter, these routers connect to Internet Service Providers (ISPs) and manage data packets between different networks.
5. Core Routers: Operating within a single network, core routers handle significant data transfers, ensuring efficient internal communication.
6. Virtual Routers: Implemented via software on virtual machines, these routers provide enhanced flexibility and scalability for network management.
7. Portable Routers: Specifically designed for mobility, these routers create private Wi-Fi networks, allowing users to connect devices on the go.

How a router works

A router analyzes the destination IP address in a packet header and cross-references it with a routing table to identify the most suitable next hop for that packet. Routing tables contain guidelines for directing data to specific network destinations, often considering additional factors like cost. Essentially, they serve as an algorithmic framework that determines the optimal route for transmitting traffic to any given IP address.

Typically, a routing table includes a default route, which the router resorts to when it cannot find a more advantageous forwarding option for a packet. For instance, a standard home-office router channels all outgoing traffic through a single default route to its Internet Service Provider (ISP).

Routing tables can be classified as either static or dynamic. Static routers are set up manually, while dynamic routers automatically refresh their routing tables based on network activity and share information with other devices using routing protocols.

Additionally, many routers implement Network Address Translation (NAT), which conceals the private IP addresses within a Local Area Network (LAN) by reassigning all outgoing traffic to a single public IP address. NAT not only helps conserve globally valid IP addresses but also enhances network security.

Features of Router

• A router operates on the Network Layer (Layer 3) of the OSI model, communicating with neighboring devices using IP addresses and subnets.
• It provides high-speed internet connectivity through various ports, such as gigabit, fast Ethernet, and STM link ports.
• Users can configure the ports to meet specific network needs.
• Key router components include a central processing unit (CPU), flash memory, RAM, non-volatile RAM, console, network, and interface card.
• Routers manage large network traffic by treating subnetworks as whole networks.
• They filter unnecessary interference and handle the encapsulation and decapsulation of data.
• Routers offer redundancy, functioning in a master-slave configuration.
• They enable connections across multiple LANs and WANs.
• Additionally, routers create diverse routes to efficiently forward data.

Router protocols

Routing protocols are essential for enabling routers to recognize each other within a network, monitor potential destinations, and make real-time decisions on message delivery. The main types of routing protocols include:

• Open Shortest Path First (OSPF): This protocol identifies the optimal path for data packets as they traverse interconnected networks. It is classified as one of the Interior Gateway Protocols by the Internet Engineering Task Force.
• Border Gateway Protocol (BGP): BGP governs packet routing across the internet by facilitating information exchange between edge routers. It enhances network stability, allowing routers to quickly reroute packets if a connection fails.
• Interior Gateway Routing Protocol (IGRP): IGRP manages how routing information is shared within an autonomous network, allowing other protocols to utilize this data for directing transmissions.
• Enhanced Interior Gateway Routing Protocol (EIGRP): EIGRP, an advancement over IGRP, queries neighboring routers when a route is not found. It minimizes updates by notifying nearby routers only of changes in routing table entries.
• Exterior Gateway Protocol (EGP): This protocol facilitates the exchange of routing information between neighboring gateway hosts, each with its own router, commonly used on the internet.
• Routing Information Protocol (RIP): As one of the earliest protocols, RIP defines how routers share information among interconnected local area networks (LANs). It limits the maximum hops to 15, which restricts its scalability.

How do routers help your business?

Routers play a crucial role in modern networking by connecting users to both local and internet networks, enabling vital business operations. Without routers, collaboration, communication, and information retrieval via the Internet would be impossible.

In addition to facilitating data transmission, routers can enhance security through built-in firewalls and content-filtering software, protecting users from harmful content while maintaining a smooth online experience.

Moreover, many routers offer additional functionalities such as connecting external hard drives for file sharing or printers accessible to all network users.

Advantages of Router

• Simplified Connectivity: The primary benefit of a router is its ability to share a single network connection among multiple devices. This allows numerous users to access the internet simultaneously, enhancing overall productivity. Additionally, routers facilitate connections across different media and network architectures.
• Enhanced Security: Installing a router is crucial for securing a network connection. Directly connecting a modem to the internet can expose your computer to various security threats. By acting as an intermediary between two networks, routers help create a more secure environment, although they do not replace firewalls or antivirus software.
• Utilization of NAT: Routers implement Network Address Translation (NAT) to convert multiple private IP addresses into a single public IP address. This improves internet connectivity and facilitates efficient data flow among all devices on the network.
• Dynamic Routing Support: Routers utilize dynamic routing techniques to optimize network communication. This method selects the best path for data transmission and establishes collision and broadcast domains, ultimately reducing network congestion.
• Packet Filtering: Routers also provide packet switching and filtering services. They apply a set of filtering rules to manage network traffic, determining which packets are permitted to pass through.

What are some of the security challenges associated with routers?

1. Exploiting Vulnerabilities: All hardware routers come equipped with firmware, which is essential for their operation. However, like any software, router firmware can have vulnerabilities that cybercriminals may exploit. Manufacturers regularly release updates to address these issues, making it vital to keep router firmware current. Failure to do so can leave routers susceptible to attacks, enabling unauthorized monitoring of traffic or incorporation into botnets.

2. DDoS Attack Risks: Both small and large organizations are often targets of distributed denial-of-service (DDoS) attacks aimed at their network infrastructure. If left unaddressed, these attacks can overwhelm routers or cause them to crash, leading to significant downtime. Solutions like Cloudflare Magic Transit can help protect routers and networks from such DDoS threats.

3. Default Administrative Credentials: Each router comes with default administrative credentials for managing settings. These are typically set to common values like “admin” for both username and password. It is crucial to change these defaults promptly; attackers are aware of these standard credentials and can gain remote access if they remain unchanged.

Applications of Routers

Routers find applications in various domains:

• They connect hardware devices with remote networks such as BSC, MGW, IN, SGSN, and other servers.
• They support high-speed data transmission through STM links, making them suitable for both wired and wireless communications.
• Internet service providers utilize routers to transmit data globally in formats such as emails, web pages, images, voice calls, or video files.
• Routers can enforce access restrictions by allowing specific users full access while limiting others to designated data.
• Software testers use routers for WAN communications; for instance, enabling collaboration between a software manager in Agra and an executive in Pune or Bangalore by connecting their PCs through WAN architecture.
• In wireless networks, routers configured with VPNs allow for the sharing of internet access, video, data, voice, and hardware resources within a client-server model.
• Modern routers often feature built-in USB ports with sufficient internal storage capacity for connecting external storage devices for data sharing.
• They are integral in establishing the operation and maintenance center (NOC) of an organization by connecting distant equipment via optical cables at a central location while providing redundancy through the main link and protection link topologies.