# Implementation of OSPF (Open Short Path First) Routing Protocol using Dijkastra Algorithm.

## OSPF is a Link State Routing Protocol that is used for construction of larger network size. In this paper, we have concentrated about OSPF protocol. Dijkstra’s algorithm is one of the best suited algorithms to find the shortest path for the given vertices. In future work we would implement OSPF protocol using NS2 simulator.

## Open Shortest Path First(OSPF):-

Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing(LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single autonomous system(AS). It is defined as OSPF Version 2 in RFC 2328 (1998) for IPV4 The updates for IPV6 are specified as OSPF Version 3 in RFC 5340 (2008).OSPF supports the Classless Inter Domain Routing (CIDR) addressing model.

OSPF is a widely used IGP in large enterprise networks IS-IS another LSR-based protocol, is more common in large service provider networks.

# Finding the shortest path in OSPF using Dijkstra’s Algorithm 👉👉

Dijkstra’s algorithm is graph traversing algorithm. In computer network we have sender and receiver, sender will send some frame or message to receiver, but by the time receiver could receive the message, there are many parts which the message can take, that is the job of this algorithm. It will find the shortest path traversed to carry the message from sender to receiver. Consider a network structure given below, the figure contains the nodes between A to H. We need to examine the shortest path, between A to D, where A being the sender and D being the Receiver.

1. During the first stage, we need to find the shortest node from the neighbor nodes of source node.

2. During the second stage, we need to look for second shortest path node, which can be a neighbor node of source node or to the node found in the first stage.

3. During the third stage, the algorithm looks for third shortest path node form the source node. This node can be neighbor of source node or the nearest node found from first stage or second stage.

4. The process repeated, until all nodes are visited at-least once and if all nodes are visited once, then we can find the shortest path form the source node to destination