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Difference between OSPF and IGRP

Last Updated : 22 Aug, 2022
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1. Open Shortest Path First (OSPF): 
OSPF uses a link-state routing algorithm. Using the link state information which is available in routers, it constructs the topology in which topology determines the routing table for routing decisions. It supports both variable-length subnet masking and classless inter-domain routing addressing models. Since it uses Dijkstra’s algorithm, it computes the shortest path tree for each route. The main advantage of the OSPF (Open Shortest Path first) are that it handles the error detection by itself and it uses multicast addressing for routing in a broadcast domain. 

2. Interior Gateway Routing Protocol (IGRP): 
IGRP uses distance vector protocol (interior) to exchange data within a system. It supports multiple metrics for each node which includes delay, load, and bandwidth, to compare the 2 routes which are combined into single metrics. The port number for IGRP is 9 which is used for communication and by default every 90 seconds it updates the routing information. 

Difference between OSPF and IGRP :

1. OSPF stands for Open Shortest Path First. IGRP stands for Interior Gateway Routing Protocol.
2. OSPF works on Dijkstra Algorithm. IGRP works on Bellman Ford Algorithm.
3. It is a link state protocol. It is a distance vector protocol.
4. It is basically used for larger size organizations in the network. It is basically used for medium to larger size organizations in the network.
5. There is no such restriction on the hop count. It allows maximum hop count up to 255.
6. It is a more intelligent routing protocol than IGRP. It is not more intelligent routing protocol.
7. OSPF routing protocol creates three Tables in the router: Neighbor Table, Database Table, and Routing Table. IGRP routing protocol creates three tables In the router: Neighbor Table, Topology Table, and Routing Table.
8. Its administrative distance is 110. Its administrative distance is 100.
9. It is an Industry standard routing protocol. It is a Cisco standard routing protocol.
10. It calculates the metric in terms of bandwidth. It calculates the metric In terms of bandwidth, load, and delay.
11. To calculate the best path SPF algorithm is used. To calculate the best path distance vector algorithm is used and the load balancing of unequal cost is done by a variance mechanism.
12. The area no. is used to create a separate administrative boundary. The routers that are within the same area able to exchange the route information with neighbor routers in the network. The Autonomous System (AS) No. is used to create a separate administrative boundary in the network.
13. VLSM (Variable Length Subnet Mask) is supported. It does not provide VLSM (Variable Length Subnet Mask).

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