Two Cisco routers are directly connected via an Ethernet link and configured to run OSPFv2 in Area 0. Router A is configured with an OSPF Hello interval of 10 seconds, while Router B is configured with an OSPF Hello interval of 15 seconds. Which outcome will occur when the OSPF process runs between these two routers?
- The routers will fail to form a neighbor relationship because OSPF Hello intervals must match exactly.Answer
- BThe routers will negotiate the Hello interval dynamically and settle on the lower timer value of 10 seconds.
- CThe routers will successfully form a neighbor relationship but will remain stuck in the 2-Way neighbor state.
- DThe routers will establish a Full neighbor adjacency, but link-state update propagation will be delayed.
Answer
The routers will fail to form a neighbor relationship because OSPF Hello intervals must match exactly.
For two routers to establish an OSPFv2 neighbor adjacency, several parameters contained in OSPF Hello packets must match exactly. These include the Area ID, Subnet Mask, Hello/Dead intervals, Authentication parameters, and Stub Area flags. Because Router A is configured with a 10-second Hello timer and Router B with a 15-second Hello timer, the routers reject each other's Hello packets and fail to form an adjacency.
Step-by-Step Solution
Key Concept
OSPFv2 Neighbor Adjacency Requirements (Hello/Dead Timers)