What is a Router and How does a Router Work?

A router is Layer 3 network gateway device. This means that a router connects two or more networks using wired or wireless connections. The router operates at the network layer (Layer 3) of the OSI (Open Systems Interconnection) model.

History of a router

The initial idea for a router, previously known as a gateway, was introduced in 1972 by an organization called the International Network Working Group.


The first actual router was developed in 1974, and by 1976, three routers were used to form an experimental version of the Internet. Routers participate in packet switching which lays the foundation for Internet’s network design.

On the other hand, network design of ARPANET (Advanced Research Projects Agency Network), the precursor of the Internet, was designed on the basis of circuit switching.

The function of a router

A router connects two or more networks and is often included as a part of a network switch. The primary feature of a router is to determine the best route for a packet to reach its destination.

Routers are present at all gateways. A gateway is a point where one network meets another. The current state of any network, whose gateway has a located router, decides the path of the data packet in transmission.

In doing so, routers use different routing protocols and algorithms. These algorithms are designed to find routes on the basis of criteria such as throughput, delay, minimum overhead, reliability, and flexibility.

The second important function of routers is to transmit information securely. The router is located at the first point where inter-network communication happens.

Routers use security measures such as WEP, WPA or WPA2 to ensure that only you can connect to the network. This also ensures that delicate information (such as credit card details and transaction histories) shared by you is safely transmitted to your bank without any chance of interception.

How does a router work?

Routers can be considered as special-purpose computers.They contain a central processing unit (CPU), digital memory and input-output (I/O) interfaces. Routers work on an embedded operating system with limited functionality and a small amount of storage space.

Cisco Internetwork Operating System (IOS) is one of the most popular operating systems for routers. These operating systems are commonly called router firmware.

You can also use an open source operating system like DD-WRT on your router to improve on optimization and features of the standard firmware that comes with your router.

Routers maintain configuration information using routing table. A router stores tables of available routes and their status. When a data packet is sent to a router, it checks for the destination address.

Based on the destination, a router calculates the next hop in the most efficient (lowest cost) path possible for the transmission. A hop refers to a path between two routers.

For example, if a data packet passes through five routers to reach its destination, we can say that it reached its destination in five hops. Achieving low cost with routing is very important because the WAN bandwidth is expensive.

Routers can also monitor incoming and outgoing traffic on the bases of the IP addresses of the sender or receiver of a data packet. This information can also be used in changing routes of a data packet to avoid congestion of the network.

Types of routers

Routers are manufactured to support different standards. Some of the commonly used Wi-Fi standards, in order of their recency, are 802.11ac, 802.11n, and 802.11g.

These routers allow networks speed specified by the standard they support. The routers with the latest specifications will cost more but will be more powerful and let much faster data exchange rates.


Three big brands that provide routers for home and offices are Linksys, Netgear, and TP-LINK. Some routers to look while purchasing one for your home are Linksys EA6500 and Netgear AC1750 (based on the 802.11ac standard), Netgear N300 WNR2000 and TP-LINK TL-WR841N (based on 802.11n standard, and Netgear WGR614 and Linksys WRT54G Wireless-G (based on 802.11g standard).

These routers are inexpensive and readily available in retail or can be ordered online from www.amazon.com.


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