Understanding Router ID and Its Role in OSPF:
In OSPF, the Router ID uniquely identifies a router within the OSPF domain. If two routers are configured with the same Router ID, it can lead to issues such as LSA conflicts and flapping. This is because the Router ID is used as a key in OSPF operations, including LSA generation and database synchronization.
HCIP-Datacom-Core Technology Training Material (OSPF Basics - Router ID and LSA Handling).
Scenario Details:
Different Areas: Even if the two routers belong to different areas, the Router ID remains globally significant in the OSPF domain. This means that any duplication of Router IDs will confuse OSPF mechanisms.
ASBR (Autonomous System Boundary Router): When one of the routers is an ASBR, it generates Type 4 and Type 5 LSAs to describe external routes. These LSAs use the Router ID asan identifier. If another router in the network has the same Router ID, conflicts occur during LSDB synchronization.
[Reference:HCIP-Datacom Advanced Routing & Switching Technology (LSA Types and ASBR Operations)., Impact of Router ID Duplication:, LSA Flapping: The OSPF process receives conflicting LSAs from routers with the same Router ID. This results in continuous updates and withdrawals of these LSAs, causing flapping., Routing Instability: LSA flapping leads to frequent recalculations of the OSPF shortest path tree (SPT), affecting overall network stability., Reference:HCIE-Datacom V1.0 Training Material (OSPF Troubleshooting and Best Practices)., Conclusion:, The statement isTRUE. LSA flapping occurs when two routers in an OSPF network have the same Router ID, even if they are in different areas and one is an ASBR. This is due to the global significance of Router IDs in OSPF and the role they play in LSA generation and propagation., , ]
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