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A router is a network device that connects your local area network (LAN) to the wide area network (WAN), also known as the internet

A router “modulates and demodulates” (or converts) the analog signal from your internet service provider (ISP) and the digital signal from your computer, smartphone, and other network devices, so you can access the internet

Routers also perform routing functions, which means they direct data packets to their destination IP address based on their internal routing table

A modem-router combo, also called a gateway, is a device that combines the functions of a modem and a router in one unit.

It simplifies your network setup by reducing the number of devices and cables you need.

A modem-router combo connects directly to your ISP’s network and provides internet access to all your devices via Wi-Fi or Ethernet ports

Different types of routers

DSL router or modem-router: This type uses a phone line to connect to your ISP’s network and provides internet access via DSL (digital subscriber line) technology. DSL routers or modem-routers can support speeds up to 100 Mbps, but they are usually slower and less reliable than cable or fiber optic types

Cable router or modem-router: This type uses a coaxial cable to connect to your ISP’s network and provides internet access via cable technology. Cable routers or modem-routers can support speeds up to 1 Gbps, but they may be affected by network congestion and interference from other users in your area

Fiber optic router or modem-router: This type uses a fiber optic cable to connect to your ISP’s network and provides internet access via fiber optic technology. Fiber optic routers or modem-routers can support speeds up to 10 Gbps, but they are more expensive and less widely available than DSL or cable types

Wireless router: This type connects to your modem via an Ethernet cable and provides wireless internet access to your devices via Wi-Fi technology. Wireless routers can support different Wi-Fi standards, such as 802.11n, 802.11ac, or 802.11ax, which affect the speed, range, and bandwidth of your wireless network

Mesh router: This type consists of multiple wireless routers that work together to create a seamless and extended wireless network throughout your home or office. Mesh routers can eliminate dead zones, improve coverage, and increase speed by using smart algorithms and multiple bands to route data packets efficiently

How they work

A router is a device that forwards data packets between different networks based on their destination IP addresses.

A router has two main functions: routing and switching.

Routing is the process of finding the best path for a data packet to reach its destination.

A router uses routing protocols, such as RIP, OSPF, EIGRP, or BGP, to exchange routing information with other routers and build a routing table.

A routing table contains entries for each network that the router can reach, along with the next hop address, the interface, and the metric.

The next hop address is the IP address of the next router that the packet should be sent to.

The interface is the physical or logical port that connects to the next hop.

The metric is a value that indicates the cost or preference of using a certain path

Switching is the process of moving data packets from one interface to another based on their destination MAC addresses.

A router uses a switching table, also known as an ARP table or a CAM table, to store the MAC addresses of the devices that are directly connected to its interfaces.

A switching table contains entries for each MAC address and the corresponding interface.

When a router receives a data packet, it first checks its destination IP address and looks it up in its routing table. If it finds a matching entry, it then checks the next hop address and looks it up in its switching table.

If it finds a matching entry, it then sends the packet out of the corresponding interface

A router performs these functions by using various components

Processor: The processor, also known as the CPU, is the main component of any router. It executes instructions and processes data at high speeds. Routers typically have powerful processors with multiple cores to handle multiple requests from devices simultaneously

RAM: RAM is the short-term memory unit that stores working data and machine code. Processors access data from RAM faster than from storage devices. Routers usually have large amounts of RAM to store and retrieve data quickly

Storage: Storage is the long-term memory unit that stores various files necessary for executing machine code. This includes operating system files, libraries, databases, website data, application data, etc. Routers use storage devices such as hard drives or solid-state drives (SSDs) to store data permanently or temporarily

Network interface: Network interface is the component that connects the router to the network. It enables the router to communicate with other devices over a network. Routers use network interfaces such as Ethernet ports, coaxial ports, phone ports, fiber optic ports, Wi-Fi antennas, etc., to transmit or receive data packets

Power supply: Power supply is the component that provides energy for efficient operation of the router. It converts AC power from the wall outlet into DC power for the device. Routers use power supply units such as adapters, batteries, solar panels, etc., to supply powe