TCS Placement: Sample Questions 142 - 142 of 502
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Question 142
Explanation
- Open Shortest Path First (OSPF) is a link state routing protocol (LSRP) using the Shortest Path First (SPF) or Dijkstra՚s algorithm to calculate shortest connection path between known devices.
- It is an Interior Gateway Protocol (IGP) routing Internet Protocol (IP) packets.
- OSPF has following advantages:
- Scales well
- Can route traffic along multiple paths
- Uses Internet՚s topology to make accurate routing decisions
- For example, to go from city A to city M there are two options:
- Travel via cities B and C. The route would be ABCM. And the distance (or bandwidth cost) for A-B is miles, B-C is miles and C-M is 10 miles.
- Travel via city F. The route would be AFM. And the distance for miles and F-M is miles.
- Shortest route has least amount of total distance.
- Thus, ABCM is the better option even though two cities have to be traversed. Second option with a single city has cost of .
- OSPF does similar calculation for shortest path between the source and destination based on link bandwidth cost.