First, let’s deal with the concept of “dynamic routing”. Up to this point, we used static routing, that is, we prescribed a routing table on each router with our own hands. The use of routing protocols allows us to avoid this tedious monotonous process and errors associated with the human factor. As the name implies, these protocols are designed to build routing tables themselves, automatically, based on the current network configuration. The thing is necessary, especially when your network is not 2 routers, and 30, for example.
Dynamic routing protocols are used for the following tasks:
1. Discovery of remote networks;
2. Update routing data;
3. Choosing the best path to destination networks;
4. Find a new optimal path if the current path is not available.
Each Protocol has its own data structures, usually tables or databases . Also, protocols send different types of messages, some to detect neighboring routers, some to exchange information about routes and some to perform other tasks related to obtaining up-to-date information about the network . Each Protocol has its own algorithm to simplify data exchange and determine the optimal path. An algorithm is a specific list of actions used to perform tasks .
Using routing protocols, routers dynamically exchange information about remote networks and automatically compare this information with their own routing tables. This is how they determine the best path or route to each network . Next, they check this route with their table . If there is no route with a smaller AD (administrative distance), this route will be added to the table .
Examples of dynamic routing protocols are: Routing information Protocol (RIP) , Open Shortest Path First(OSPF), Enhanced Interior Gateway Routing Protocol(EIGRP). There are different versions of protocols for IPv4 and IPv6 addressing. In more detail in the lesson we got acquainted with the RIP Protocol. Now it is not used, as the maximum it can expand to 16 routers in the network . But it is used as an example for understanding.
Computer Networks 