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352-001 · Question #1
352-001 Question #1: Real Exam Question with Answer & Explanation
The correct answer is B: At some hardware platforms, BFD and NSF are not supported together. During supervisor engine or. NSF and BFD interaction is platform-dependent - some platforms cannot maintain BFD sessions during supervisor failover, and BFD packets must continue flowing to prevent the peer from declaring a false link-down.
Question
A company plans to include Nonstop Forwarding and Bidirectional Forwarding Detection as a part of their network redundancy plan. In which two ways do NSF and BFD work together when different hardware platforms are compared? (Choose two.)
Options
- ADuring supervisor engine or routing engine failover, the NSF feature will always ensure that the BFD
- BAt some hardware platforms, BFD and NSF are not supported together. During supervisor engine or
- CTo ensure that BFD at the peer router will not trigger a link down during NSF, the BFD packets must
- DBecause BFD is always processed at the line cards (not at the supervisor engine or routing engine),
- EBecause BFD is always processed at the supervisor engine or routing engine, a supervisor engine or
Explanation
NSF and BFD interaction is platform-dependent - some platforms cannot maintain BFD sessions during supervisor failover, and BFD packets must continue flowing to prevent the peer from declaring a false link-down.
Common mistakes.
- A. NSF does not universally guarantee BFD session continuity during failover - whether BFD survives a supervisor restart depends entirely on the hardware platform and where BFD processing is performed.
- D. BFD is not always processed at the line cards - on many platforms it is handled by the supervisor or routing engine, so stating it is always at the line cards is factually incorrect.
- E. BFD is not always processed at the supervisor or routing engine - on platforms that support hardware-offloaded BFD, it runs on line cards and survives supervisor failover, making this absolute statement incorrect.
Concept tested. NSF and BFD interoperability during supervisor failover
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