IPreittejä

IPreittejä, or IP routes, are rules used by IP routers to forward packets toward their destinations. Each route specifies a destination network (an IP prefix) and a next-hop address or exit interface. Routers maintain routing tables that store active routes and are consulted by the forwarding plane to determine how to forward each incoming packet.

Routes can be static or dynamic. Static routes are manually configured and do not change unless edited. Dynamic routes are learned automatically using routing protocols, enabling automatic adaptation to topology changes and network conditions.

Common routing protocols include RIP, OSPF, EIGRP, and BGP. These protocols differ in how they discover routes: RIP is a distance-vector protocol that uses hop count; OSPF is a link-state protocol that assigns costs based on link metrics; EIGRP is a hybrid protocol with a composite metric; BGP is a path-vector protocol used to exchange routing information between autonomous systems on the Internet.

IPv4 and IPv6 use similar concepts; routes are represented as prefixes with a prefix length. A route entry includes the destination prefix, a next-hop address or exit interface, an administrative distance, and a metric. When multiple routes to a destination exist, the router selects the route with the lowest administrative distance, then the best metric, and finally the longest prefix match in practice.

Default routes, route aggregation, and summarization help manage routing tables and improve scalability. Convergence and stability are important considerations, as routing protocols must agree on new best paths after topology changes. Routes can also be redistributed between protocols to integrate different parts of a network.