Routers support direct, static, and dynamic routes. Dynamic routes include Routing Information Protocol (RIP) routes, Open Shortest Path First (OSPF) routes, Intermediate System-to-Intermediate System (IS-IS) routes, and Border Gateway Protocol (BGP) routes.
Static routes are easy to configure, have low system requirements, and apply to simple, stable, and small networks. The disadvantage of static routes is that they require subsequent maintenance as they cannot automatically adapt to network topology changes.
Dynamic routing protocols have routing algorithms. Therefore, dynamic routes can automatically adapt to network topology changes and apply to networks on which Layer 3 devices are deployed. The disadvantages of dynamic routes are that they are complex to configure, have higher system requirements than static ones, and consume network and system resources.
Dynamic routing protocols are classified based on the following two criteria.
According to the application range, dynamic routing protocols are classified into the following types:
Interior Gateway Protocols (IGPs)
Run inside an autonomous system (AS), including RIP, OSPF, and IS-IS.
Exterior Gateway Protocols (EGPs)
Run between ASs, including BGP.
According to the type of algorithm they use, dynamic routing protocols are classified into the following types:
Distance-vector routing protocols
Include RIP and BGP. BGP is also called a path-vector protocol.
Link-state routing protocols
Include OSPF and IS-IS.
The preceding algorithms differ mainly in route discovery and calculation methods.