Routering

Routering is the process of directing data packets from a source network to a destination network through one or more routers. It relies on routing tables and decision algorithms to determine the next hop for each packet. In common networking usage, routing describes the overall process, while routering refers to the actions taken by routers to move traffic between networks.

Routers operate at the network layer (layer 3) of the OSI model and use IP addresses to determine paths. A router’s routing table lists routes with next-hop information, interfaces, and metrics that influence path selection. Routes can be static (manually configured) or learned dynamically through routing protocols. IPv4 uses longest-prefix matching for destination addresses; IPv6 uses a similar principle with a larger address space.

Dynamic routing protocols include RIP, OSPF, EIGRP, and BGP. These protocols exchange topology information to adapt to network changes, enabling automatic recalculation of optimal paths. Routing decisions may involve route aggregation or summarization, as well as load balancing across multiple equal-cost paths. Networks may also implement policy-based routing to influence route selection based on criteria beyond simple metrics.

Forwarding is distinct from routing: routing determines the path, while forwarding moves the packet to the next hop. Routers may apply access control lists, quality of service, and other traffic-management or security policies during forwarding. Security concerns in routering include misrouting, route hijacking, and route leaks, which can affect connectivity and trust.

Historically, static routing gave way to dynamic protocols as networks grew. Today, interdomain routing is primarily handled by BGP, while interior networks commonly use OSPF or EIGRP. Ongoing developments focus on automation, scalability, and more granular control over traffic flows through advanced routing techniques.