OSPF Protocol

OSPF Protocol stands for open shortest path first.

Its a routing protocol for Internet Protocol networks.
If network is based on IP, the OSPF algorithm will calculate the most efficient way for data to be transmitted.
OSPF has largely replaced RIP protocol in most of corporate 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).

Following diagrams will help you understand why OSPF protocol is necessary !!

Basic network topology with data flow.

If we see above network the data/traffic from source to destination is going via router A-H-D.
Let assume this path is the primary and is assigned by user after calculating the shortest path manually.Whenever, there will be any issue in the network the user needs to manually check shortest path and reassign.
Which is definitely cumbersome and time consuming if user have a huge network with many routers.

Fibre cut between router A and H

In above image you can see here there is fibre cut between router A-H.
your network has two paths to transmit data from source to destination.
OSPF will end up sending traffic the best available shortest path i.e. A-B-C-D.

Looking at below image, when only one path is available, then traffic will be sent via that path. As no other route is available for data transmission.

Two fibre Cut and only one path

The above example is to make you understand that OSPF plays a vital role when a user has huge network with multiple routes.

Selecting shortest route will help reduce down the time of traffic transmission drastically.

There are many other routing protocol which provides more optimized routing solutions for data transmission.

To understand basic working of OSPF please visit below link
OSPF basic working and LSDB

Advantages of OSPF protocol over RIP ( Routing information protocol)

1. It uses link state routing protocol which is faster that distance vector.
2. It supports multi casting.
3. Its Matrix is dependent on Bandwidth and not on hop count.
4. It also support unlimited hops
5. Update is based on triggered events only. (Only when change in topology or route happens)