By most definitions, the purpose of a network router is defined by its name—it routes packets from one location to another. But over the decades of Internet networking, the value of routers has grown significantly, providing businesses with additional features such as network security, content filtering, quality of service, and more.
At its most basic level, a router is a device that connects networks to each other, forwarding data packets from one location to another until they reach their destination. In a local area network (LAN), a router can also allow multiple devices to use the same Internet connection, such as how a home router allows users to connect their laptops, phones, and tablets (as well as countless other devices) simultaneously.
How does a router work?
Digital content, whether it’s an email from an employee to a customer or a live video conference call, is delivered in packets across corporate networks and the global Internet. These packets contain a destination address; for example, an IP address if the data is transmitted over the Internet.
Routers determine the fastest path (or “route”) a packet can take to deliver its payload. This is similar to how a GPS app on your smartphone calculates the fastest route to your destination, including all turns and roads to take, but also takes real-time traffic conditions into account.
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A key difference is that each individual router along the way does not determine the complete route, but only the next connection to the final destination. Routers do this by consulting internal routing tables – lists of paths to various network destinations.
The router reads the packet’s header to determine where it needs to go, and then forwards the packet to the next network router in the most efficient path. Many routers also include the ability to tell other packets which routes to take, or to forward packets to a different route to a given destination based on current conditions (such as heavier network traffic). This is often called dynamic routing or adaptive routing, in contrast to static routing, where the route through the network is usually the same path.
In a home or small office network setup, the router connects to a modem or gateway that connects an Internet connection (typically broadband provided by an Internet service provider) to the home or business. Routers include Ethernet ports for connecting devices to the network, or they provide wireless capabilities (via Wi-Fi) to connect devices such as laptops, smartphones, or tablets.
A home or small office usually only requires a network router to provide LAN connectivity and Internet connectivity. Midsize companies and enterprises often use multiple routers to connect devices within the LAN and then to edge routers to connect to the Internet (see below for different router types).
What is the difference between a router and a switch?
Routers are sometimes confused with switches, which also provide forwarding and routing of network traffic but serve a different purpose. Routers operate at layer 3 (network layer) and are basically used to connect networks to other networks.
Switches, on the other hand, typically operate at Layer 2, connecting and classifying packets to distribute traffic to devices within the LAN. Some switches can operate at Layer 3, and some routers can perform switching tasks, but generally switches operate on the LAN, and routers usually connect the LAN to the Internet and other routers on the wide area network (WAN).
What is the difference between a router and a modem?
A modem (or gateway) is the device that connects the Internet link provided by your ISP (usually a broadband connection such as cable, fiber optic, or DSL) to your home or business. A modem or gateway can then be connected to the router to provide a direct wired connection to a single computer or, more typically, multiple connections to devices on the LAN (computers, phones, tablets, game consoles, TVs, refrigerators, etc.) .
What are the different types of routers?
Routers come in many different sizes, depending on the number of devices that need to be connected or the capabilities of the router. Typically, routers fall into one of the following categories:
Core Routers: Typically used by large enterprises, ISPs, and cloud service providers, these types of routers transport large amounts of data packets within the network. Sometimes these core routers are part of the “Internet backbone.” They typically run at the “core” of the network, hence the name.
Edge Router: An edge router is basically a router that communicates with the core router and external networks, usually at the “edge” of the network. These networks utilize Border Gateway Protocol (BGP) to send and receive data from other LANs and WANs.
Wired Routers: These routers typically include Ethernet ports, allowing LAN connections for devices that use Ethernet as their primary network connection. Other network equipment in the data center, as well as older desktop computers without wireless capabilities, will be connected to the wired router.
Wireless routers: Similar to wired routers, these routers include a radio that converts digital signals into radio waves. A laptop or other mobile device typically sends data wirelessly to one of these routers. In large organizations, wireless access points (rather than routers) help transmit data to wired routers before the data is sent over the Internet. However, some wide area routers (such as a 4G or 5G wireless card that can be connected to a laptop) provide Internet connectivity and include a wireless router within it. For example, a smartphone that can share its 4G/5G connection with other users basically acts like a wireless router.
Virtual router: A software application that performs the same functions as a hardware router – this is often used in software-defined networking (SDN)
What other functions does the router have?
Routers increasingly perform additional functions for enterprises, and these functions are either placed on the router itself, or the router connects to other hardware devices to perform these tasks. For example:
Firewall: Many routers include firewall functionality to prevent malicious traffic from entering the network, or they can be connected to a standalone firewall network device (in the case of larger enterprises).
Quality of Service (QoS): For companies that need to prioritize certain types of traffic over others, such as video conferencing over email, QoS features can create those priorities (like creating a high-occupancy highway that prioritizes carpooling) Lane).
Various network settings: The router can create a guest network that provides Internet access only, limiting access to other devices on the LAN, or the router can use the network access feature to limit what end users on the network can access to specific servers or computers on the LAN (e.g. Restrict access to HR servers or files to most employees).
Over time, the capabilities of routers will continue to evolve beyond the basic function of just forwarding packets from one location to another, as companies leverage their devices and software to perform additional or highly specific tasks.
Keith Shaw is a freelance technology journalist who has been writing about a variety of technology topics for more than 20 years, including networking, consumer electronics, robotics, and the future of work.