On the Internet, network connecting devices such as hubs, bridges, switches, and routers control traffic and ensure data transmission quality. Each of these devices serves as a different role, but for a common purpose: forming a functioning network. The following describes a router's role in a network, and the purpose and nature of routes.
A router selects routes and forwards packets. Upon receiving a packet, a router selects a proper path, which may have one or more hops, to send the packet to the next router according to the destination address in the packet. The last router is responsible for sending the packet to the destination host.
A route is a path along which packets are sent from the source to the destination. When multiple routes are available to send packets from a router to the destination, the router can select the optimal route from an IP routing table. Optimal route selection depends on routing protocol preferences and metrics of routes. When multiple routes have the same routing protocol preference and metric, load balancing can be implemented among these routes to relieve network pressure. When multiple routes have different routing protocol preferences and metrics, route backup can be implemented among these routes to improve network reliability.