OSPF Routing Protocol:
How it Works and Why It Matters?
You might just heard about OSPF, but did you realize it’s been around your office environment the whole time?
OSPF stands for Open Shortest Path First. Don't worry about the technical name. In essence, OSPF is a 'language' or protocol used by routers to communicate with each other and share information about the condition of the network around them. Imagine that each router is like a lookout that observes the road around it: whether the road is smooth, congested, or even closed. This information is then shared with other 'spotters' so that everyone has a complete picture of traffic conditions.
How OSPF Works?
How these ‘spotters’ shares their informations?
Befriending Neighbors
First, each router will search and ‘get acquainted’ with its directly connected neighboring routers. They form a relationship called ‘adjacency’. It’s like building a small team at every crossroads.
Sharing ‘Roadmap’ Information
Once befriended, each router will create a simple ‘roadmap’ of itself and the roads (links) it is connected to, including the ‘state’ of the road (e.g., how fast it is going or how busy it is). This ‘roadmap’ information is called a Link-State Advertisement or LSA.
Disseminating the Map to Everyone
The router will then broadcast this LSA to all other routers in the same network area. The dissemination process is like spreading an important announcement throughout the city. Each router will receive a copy of the information from all other routers.
Building a Complete Map
With all the LSA information received, each router will have a complete ‘map’ of the entire network area. They know all the routers and all their connecting paths, along with the ‘state’ of each path.
Finding the Shortest Path
Now, with this complete ‘map’, each router will use a clever algorithm called Dijkstra (pronounced: Daykstra) to calculate the shortest path to each destination on the network. This algorithm is like finding the fastest route on a digital map. The router will choose the path with the smallest ‘cost’, where this ‘cost’ can be link speed or other factors.
Creating a Route Table
The results of this shortest path calculation will be stored in the router’s routing table. This table is a guide for routers to forward data packets to the correct destination via the best path that has been found.
Why It Matters?
Why is it so Popular?
Intelligent and Efficient
OSPF sends only change information, not the entire routing table periodically like other simpler protocols. This makes bandwidth usage more efficient.
Fast Adapting
If there are changes in the network, such as broken links or new routers added, OSPF will quickly propagate this information and recalculate the best path. This makes the network more stable and responsive.
Scalability
OSPF is designed to work well in large and complex networks.
Open Standard
Because of the 'Open' in the name, OSPF is an open standard supported by various network device vendors. So, we are not stuck with just one brand.
So, think of OSPF as a sophisticated navigation system for computer networks. Each router becomes a 'lookout' that shares information on road conditions, and with a complete map in hand, they can find the fastest and most efficient path to transmit data. With its intelligent, adaptable, and scalable capabilities, OSPF is the backbone of many large networks around the world, including perhaps the network you use every day. Hopefully, this explanation can provide a clearer picture of how the OSPF routing protocol works.
Thank you! ^^
“If You Don’t Know Where You are Going,
Any Road Will Get You There.”
Lewis Carroll
(Alice in Wonderland)
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