• सुखार्थी त्यजते विद्यं विध्यार्थी त्यजते सुखम्सु sखर्थीन: कुतॊ विद्या कुतॊ विध्यार्थीन: सुखम् ||
  • “Luxury people leave knowledge, but a student leaves Luxury No knowledge for one who seeks Luxury, No luxury for student”
  • न चोर हार्यं न च राज हार्यं न भात्रू भाज्यं न च भारकारि |व्ययं कृते वर्धत एव नित्यं विद्याधनं सर्वधनप्रधानम ||
  • Cannot be snatched away by thief, cannot be snatched away by king, Cannot be divided among brothers, Not heavy either If spent daily, it always keeps growing. The wealth of knowledge is the precious of wealth of all”

Open Shortest Path First Protocol




Introduction

Open Shortest Path First (OSPF) is another Interior Gateway Protocol. OSPF was created because the Routing Information Protocol (RIP) was increasingly incapable of serving large inter-networks. OSPF is based on the Shortest Path First algorithm, which is also referred to as the Dijkstra’s algorithm. OSPF is a link-state routing protocol as it sends state of all other routers. This protocol is open, which means anyone can implement it without paying license fees. It supports both IPv4 and IPv6 routed protocols. There are certain disadvantages of OSPF also, it requires extra CPU process to run SPF algorithm, it requires more RAM and is more complex to setup and hard to troubleshoot.

Link State of can be measured using following metrics:

  1. Measuring link utilization
  2. Number of hops (hop count)
  3. Speed of the path
  4. Packet loss (router congestion/conditions)
  5. Latency (delay)
  6. Path reliability
  7. Path bandwidth
  8. Throughput
  9. Load on link
  10. MTU maximum transmission unit

Example

In the given network find the shortest distance from node A to node H using  Dijkstra algorithm / OSPF /  Link State algorithm.

Solution Using Dijkstra Algorithm create following table:

We have shortest path   A to G to  H   with value  10

We can also have alternate path  A to E to H  with value 10