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

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.

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.

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.

OTV uses a MAC-routing control plane to distribute Layer 2 reachability across data centers without flooding unknown unicast traffic or propagating spanning tree BPDUs across the WAN boundary. This containment of Layer 2 state and failure domains is the defining fault-isolation characteristic of OTV. No other option listed combines inter-DC Layer 2 extension with native, built-in fault isolation.

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.