OSPF Routing Protocols

• OSPF is an open standard routing protocol, it means it is implemented for large scale that are not used by other routing protocols either it is a distance vector(RIP) or hybrid protocol (EIGRP), and it works on a variety of network vendor including Cisco. It uses Dijkstra algorithm, i.e. best for implementing in a hierarchical design. 

• OSPF introduce the concept of areas for managing and controlling the network traffic. It creates a neighbor relationship with adjacent routers in the same area.

• OSPF provides hierarchical network design with multiple different areas and all other areas must be connected to the area 0. 

• OSPF uses a multicast address (224.0.0.5) for routing updates (all OSPF routers), but all designated routers use the different multicast address (224.0.0.6) for routing updates.

• OSPF is a link-state routing protocol which is also known as “shortest path first” protocol.

• It creates three separate tables for understanding the inter-network.

• First table gets all the information about directly connected neighbor. 

• Second table determines the topology of the entire inter-network. 

• Third tables used as routing table.

• OSPF consists of the areas and autonomous systems. 

• It have unlimited hop count.

• On OSPF routing overhead is decreased and convergence is faster. 

• It sends the packets after every 5 seconds. 

• It also supports authentication. 

• It only supports equal cost load balancing. Metric is cost (cost= 10^8/b.w).