Editing Routing (section)

{{Short description|Process of selecting paths in a data communications network}}
{{About|routing in packet switching networks}}
{{Use American English|date=December 2019}}

'''Routing''' is the process of selecting a path for traffic in a [[Network theory|network]] or between or across multiple networks. Broadly, routing is performed in many types of networks, including [[circuit-switched network]]s, such as the [[public switched telephone network]] (PSTN), and [[computer network]]s, such as the [[Internet]].

In packet switching networks, routing is the higher-level decision making that directs [[network packet]]s from their source toward their destination through intermediate [[network node]]s by specific packet forwarding mechanisms. [[Packet forwarding]] is the transit of network packets from one [[Network interface controller|network interface]] to another.  Intermediate nodes are typically [[network hardware]] devices such as [[Router (computing)|routers]], [[gateway (telecommunications)|gateways]], [[Firewall (computing)|firewalls]], or [[network switch|switches]]. General-purpose [[computer]]s also forward packets and perform routing, although they have no specially optimized hardware for the task.

The routing process usually directs forwarding on the basis of [[routing table]]s. Routing tables maintain a record of the routes to various network destinations. Routing tables may be specified by an administrator, learned by observing network traffic or built with the assistance of [[routing protocol]]s.

Routing, in a narrower sense of the term, often refers to [[IP routing]] and is contrasted with [[bridging (networking)|bridging]]. IP routing assumes that [[network address]]es are structured and that similar addresses imply proximity within the network. Structured addresses allow a single routing table entry to represent the route to a group of devices.  In large networks, structured addressing (routing, in the narrow sense) outperforms unstructured addressing (bridging). Routing has become the dominant form of addressing on the Internet. Bridging is still widely used within [[local area network]]s.