Chapter 2 Advanced Routing for FortiOS 5.0 : Dynamic Routing Overview : What is dynamic routing? : Dynamic routing protocols
  
Dynamic routing protocols
A dynamic routing protocol is an agreed-on method of routing that the sender, receiver, and all routers along the path (route) support. Typically the routing protocol involves a process running on all computers and routers along that route to enable each router to handle routes in the same way as the others. The routing protocol determines how the routing tables are populated along that route, how the data is formatted for transmission, and what information about a route is included with that route. For example RIP, and BGP use distance vector algorithms, where OSPF uses a shortest path first algorithm. Each routing protocol has different strengths and weaknesses — one protocol may have fast convergence, while another may be very reliable, and a third is very popular for certain businesses like Internet Service Providers (ISPs).
Dynamic routing protocols are different from each other in a number of ways, such as:
Classful versus classless routing protocols
Interior versus exterior routing protocols
Distance vector versus link-state protocols