What are two similarities between OSPF and IS-IS? (Choose two.)
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A. B. C. D.AB
Sure, here's a detailed explanation:
OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System) are two popular link-state routing protocols used in computer networks. Both protocols have some similarities in their operation, which include:
Use of Hello packets: Both OSPF and IS-IS use hello packets to establish and maintain adjacencies with other routers in the network. The hello packets contain information about the router's ID, the network type, and the priority of the router. This helps to form a neighbor relationship between routers and ensure that the network topology is accurate.
Use of Dijkstra algorithm: OSPF and IS-IS use the Dijkstra algorithm to compute the shortest path tree (SPT) and find the best path to a destination network. The Dijkstra algorithm is a well-known algorithm used to find the shortest path in a weighted graph. By using this algorithm, both OSPF and IS-IS can determine the best path to a destination network and forward packets along that path.
However, there are also some differences between OSPF and IS-IS. For example, OSPF uses a hierarchical network design with areas, while IS-IS does not have a concept of areas. OSPF also elects a designated router (DR) and backup designated router (BDR) in each broadcast domain, while IS-IS does not have a DR/BDR election process. Additionally, OSPF supports multiple metrics, such as bandwidth, delay, and cost, while IS-IS only supports a single metric, which is the administrative distance.
Lastly, option D is incorrect, as OSPF has a built-in mechanism to provide address summarization between areas, but IS-IS does not have this feature. OSPF can summarize networks at the area boundaries to reduce the amount of routing information exchanged between routers and improve network efficiency.