Comprehensive and Detailed In-Depth Explanation:
BFD (Bidirectional Forwarding Detection)detectslink failuresfaster than traditional mechanisms.
Session states during setup:
AdminDown→ Initial state (session is administratively disabled).
Down→ The session is being established but has not yet exchanged valid control packets.
Init→ The session is partially established (one side has detected the peer).
Up→ The session is fully operational (not part of the setup process).
SinceAdminDown, Down, and Initare involved insession setup, the correct answers areB, C, D.
????Reference:Huawei HCIA-Datacom Study Guide, BFD Session Establishment and States.
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