Open Shortest Path First is one of the link state routing protocols used in Internet Protocol networks developed explicitly for the TCP/IP Internet environment. It is an Interior Gateway routing protocol defined in RFCs 1245, 1247, 1253 and 1583. The characteristics of the OSPF protocol are as follows• Provides authentication of routing messages.• Enables load balancing by allowing traffic to be split equally on routes with the same cost.• Type of Service routing allows you to set different routes based on the TOS field.• Supports subnetting.• Supports multicasting.• Allows hierarchical routing. In the shortest path-based protocol each router has an identical database describing the autonomous system (AS), each of these databases consists of information about the router's current state, reachable neighbors, and other information. The process in which the AS obtains information from the routers is called flooding. All the first shortest path routers run their algorithms in parallel, building shortest path trees with themselves as roots, when an external path is added to the trees such routers are called leaves. Externally derived data can be transparently sent to the autonomous system. There are two types of areas in the autonomous system which decides whether the route to the destination is in the area or belongs to another area, when the route to the destination is within an area it is called intra-area routing or if the route to the destination belongs to another area it is called inter-area routing. OSPF generally combines a group of networks into a set called an area. In an area the topology of a network is hidden from the rest of the networks, this thus reduces the routing traffic....... half of paper...... BDR.• This network requires the configuration of its statics neighbors.• Hello packets in this network are sent via unicast every 30 seconds and the dead timer is 120 seconds. OSPF routers are classified into four types1) Internal Routers: In internal router packets are routed within a single area. If the internal router has no interfaces to other areas, it may also be a backbone router.2) Area Boundary Routers: These routers have multiple interface areas and route packets between these areas. Area Border Routers condense topological information before sending it to the backbone, thus reducing the routing information carried to the backbone.3) Backbone Router: The backbone router has an interface on the backbone area.4) Autonomous System Router : Autonomous system routers exchange information with other autonomous systems.