Router (computing)
Device that directs data packets across computer networks.
A router is a computer and networking device that forwards data packets between computer networks, including internetworks such as the global Internet. Routers perform the traffic directing functions on the Internet, reading network addresses in packet headers and using routing tables or policies to direct packets to their next destination. They are essential for connecting home networks, enterprises, and internet service providers, and range from small office/home office models to powerful core routers that handle high-speed data along the Internet backbone.
- field
- Computer networking
- known_for
- Forwarding data packets between networks, enabling internetworking
Lore & Background
Modern routers handle IPv4 and IPv6, and high-speed models use network processors or specialized hardware with acceleration for functions like IPsec encryption.
Reader's Guide
Routers are foundational to modern internetworking, enabling the global Internet by directing data packets between diverse networks. Their development from early software-based forwarding on CPUs to application-specific integrated circuits (ASICs) has dramatically increased performance and added advanced filtering and firewall capabilities. The hierarchical internetworking model divides enterprise networks into access, distribution, and core layers, with routers optimized for each role—from low-cost SOHO models to powerful core routers interconnecting ISPs. The control plane maintains routing tables and builds a forwarding information base, while the forwarding plane handles packet forwarding. Routers have evolved from general-purpose minicomputers to specialized embedded systems, with operating systems like Cisco IOS, Junos, and NX-OS. Their significance lies in enabling connectivity within enterprises, between enterprises and the Internet, and among ISPs, supporting both wired and wireless transmission. The end-to-end principle, which leaves reliable delivery to hosts, remains a key design concept.
Did You Know?
- Early routers used software-based forwarding on a CPU; more sophisticated devices now use application-specific integrated circuits (ASICs).
Frequently Asked Questions
What is a router in computing?
A router is a networking device that forwards data packets between separate computer networks by inspecting the address in each packet's header and consulting a routing table to pick the next hop. It is the core mechanism that makes internetworking possible, from a home Wi-Fi box to the global Internet.
How does a router decide where to send a given packet?
It reads the destination network address stored in the packet header and matches it against a routing table or a set of policy rules to determine the next network to forward the packet to. This lookup-and-forward cycle repeats at each hop until the packet reaches its final destination.
Why are routers considered essential to modern networking?
Without routers, isolated networks could not exchange data, so the interconnected Internet simply would not exist. They cover an enormous range of scale, from small office/home-office units to high-speed core routers that carry backbone traffic across continents.
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