300-320 · Question #2
What is the maximum number of neighbors that a router should have in an OSPF area?
The correct answer is C. 60. Cisco design best practices recommend that a single router should have no more than 60 OSPF neighbors to avoid excessive Hello processing and adjacency overhead.
Question
What is the maximum number of neighbors that a router should have in an OSPF area?
Options
- A5
- B30
- C60
- D99
How the community answered
(47 responses)- A2% (1)
- B4% (2)
- C94% (44)
Why each option
Cisco design best practices recommend that a single router should have no more than 60 OSPF neighbors to avoid excessive Hello processing and adjacency overhead.
5 neighbors is far below the design guideline and would unnecessarily fragment network topology.
30 neighbors is below the recommended maximum and is not the figure cited in Cisco OSPF scalability guidelines.
Cisco recommends capping OSPF neighbors per router at 60 to prevent the router from being overwhelmed by Hello packet processing, adjacency maintenance, and Database Exchange operations. Beyond this limit, the CPU and memory burden of maintaining adjacencies can degrade routing stability and convergence time.
99 neighbors exceeds the recommended ceiling and would impose excessive adjacency and Hello processing load on the router.
Concept tested: OSPF neighbor scalability design limit
Source: https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/7039-1.html
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