Basic CS-Networks [3i Infotech Placement]: Sample Questions 28 - 29 of 90
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Question 29
Explanation
- Stands for Open Shortest Path First.
- A routing protocol for internet protocol.
- Used a link state routing algorithm and falls into the group of interior gateway protocols, operating within a single autonomous system.
- Outing protocol has largely replaced the older Routing Information Protocol in corporate networks.
- Link-state routing protocol means that the routers exchange topology information with their nearest neighbour.
- Calculates end-to-end paths through the autonomous system using a variant of the Dijkstra algorithm.
Working of OSPF
- OSPF network works based on area and autonomy.
- OSPF network divided into groups called areas- OSPF is based on functional areas like a building or the floor of a building.
- Autonomous systems (AS) are collections of areas- for example, every router in an organization cab probably be part of a single AS. These regions are automatically configured and routed by the router.
Advantages:
- A link state routing protocol like OSPF provides complete knowledge of topology allowing routers to calculate routes satisfying particular criteria- shortest distance, least cost, least time, best QoS etc.
- For traffic engineering purpose, route can be constrained to meet particular quality of service.
Disadvantages:
- Link state routing protocol does not scale well with more routers in the routing domain.
- Number of routers increases the size and frequency of the topology updates, and time taken to calculate routes.