Router (computing)

A router is a special kind of computer that helps send information between different networks, like the Internet. It connects to two or more networks and decides where to send each piece of information, called a data packet, so it reaches the right place.

When a packet arrives, the router looks at its address and uses a list called a routing table to choose the best path. The packet then moves from one router to another until it arrives at its destination.

Most people know routers as the devices used at home or in small offices. These routers connect computers in a house to the Internet. Bigger routers are used by companies and Internet providers to send information quickly over long distances. Some routers are built using regular computer parts, while others use special chips to work faster and include extra safety features like firewalls.

History

The idea of a device that could connect and manage different networks began in 1966, when Donald Davies suggested using software to direct data. This idea was later used in the ARPANET, an early version of the internet, with special computers called Interface Message Processors.

In the 1970s, researchers developed the first true routers. These devices could connect different types of networks and let data travel between them without needing to make sure it arrived safely. This helped create the internet we use today. Early routers were built using computers, but modern ones are very fast and have special parts to handle data quickly.

Operation

When many routers work together in connected networks, they share information about where to send data using a special set of rules called a routing protocol. Each router creates a list, called a routing table, that shows the best paths to send data between different computers.

Routers have two main parts that work together. The control plane keeps the routing table and decides the best way to send each piece of data. The forwarding plane actually moves the data packets from one connection to another, using the information from the control plane to choose the right path.

Applications

A router can connect to different types of wires, like copper cables, fiber optic lines, or wireless signals. It helps move information between different computer networks. Routers can link groups of computers called subnets, each with its own network prefix.

Routers are used in homes, offices, and big companies. Big routers connect many internet services, while smaller ones are for everyday home or office use. Routers help manage traffic and keep things running smoothly, whether in a small office or a large company.

Access, core and distribution

The hierarchical internetworking model splits big networks into three parts: core, distribution, and access.

Access routers are small and found in homes or small offices. They are made to be cheap and simple.

Distribution routers collect information from many access routers. They help manage the flow of information across larger areas and can connect to servers or other networks.

In big companies, a core router links many parts of the network together. These routers are made for speed but might not have all the extra features of other routers.

Security

Routers can help keep networks safe. They might include a firewall or tools for secure connections, and they often change network addresses to protect information. Some people think that routers with open code are safer because problems can be found and fixed more easily.

Routing different networks

Routers can be different depending on where they work. One type works inside a single group’s network, another type works on the bigger internet, and a third type links a group’s network to the internet or bigger networks.

Internet connectivity and internal use

Big companies and internet service providers use special ways to share information between their routers. There are different kinds of routers for different jobs, like connecting to other companies or handling important traffic inside a big network.

Some routers help connect home networks to the internet, and others handle phone, video, and other types of information. Bigger networks might use special switches to connect many parts together.

Wi-Fi routers

Main article: Wireless router

Wi-Fi routers do the jobs of a router, a switch, and a wireless point all in one. They are small devices that plug into a wall and give internet through wires or wireless signals for homes or offices. They connect to the internet from an Internet service provider and let devices use the internet through Ethernet or Wi-Fi.

Forwarding

Further information: Routing and IP routing

A router helps connect different networks and decides where to send data packets. It looks at the destination address in each packet to choose the best path. Routers use a special list called a routing table to make these decisions.

Routers also manage traffic when too many packets arrive at once. They have different ways to handle this, like dropping some packets to keep things running smoothly. They can also prioritize certain types of traffic, like voice calls, to make sure they sound clear. Some tasks are done quickly by special parts inside the router, while others need the router's main brain to handle them carefully.