352-001 Question #284: Real Exam Question with Answer & Explanation

The correct answer is D: OTV. OTV (Overlay Transport Virtualization) is the correct choice because it extends Layer 2 between data centers while natively isolating Layer 2 fault domains, preventing spanning tree and broadcast storms from crossing site boundaries.

Question

Which mechanism provides a Layer 2 fault isolation between data centers?

Options

ATRILL
BLISP
Cadvanced VPLS
DOTV
Efabric path

Explanation

OTV (Overlay Transport Virtualization) is the correct choice because it extends Layer 2 between data centers while natively isolating Layer 2 fault domains, preventing spanning tree and broadcast storms from crossing site boundaries.

Common mistakes.

A. TRILL provides multi-path Layer 2 forwarding using IS-IS within a single domain and does not isolate fault domains between geographically separate data centers.
B. LISP is a Layer 3 overlay for endpoint-ID and routing-locator separation; it does not operate at Layer 2 and provides no Layer 2 fault isolation.
C. Advanced VPLS extends Layer 2 over MPLS but still propagates spanning tree topology and floods broadcasts to all connected sites, providing no fault containment between data centers.
E. Fabric Path is Cisco's intra-data-center TRILL implementation used within a single DC switching fabric and is not designed for inter-DC connectivity or inter-site fault isolation.

Concept tested. OTV inter-data-center Layer 2 extension with fault isolation

Reference. https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus7000/sw/otv/config_guide/b_Cisco_Nexus_7000_Series_NX-OS_OTV_Configuration_Guide.html

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