A green data center is being deployed and a design requirement is to be able to readily scale server virtualization. Which IETF standard technology can provide this requirement?

Data Center Bridging (DCB) is an IEEE 802.1 standard set focused on providing lossless Ethernet for storage and high-performance computing traffic - it is not an IETF standard and does not specifically address Layer 2 scalability for virtualization.

Unified Fabric is a Cisco commercial term for converging LAN, SAN, and inter-process communication onto a single network infrastructure - it is not a defined IETF standard.

TRILL is formally defined in IETF RFC 6325 and uses IS-IS to provide loop-free multipath forwarding at Layer 2, eliminating spanning tree's single active path limitation. This allows data center fabrics to scale horizontally with many equal-cost paths, which is essential for scaling server virtualization workloads across large broadcast domains.

FabricPath is a Cisco proprietary implementation conceptually similar to TRILL but developed independently - it is not an IETF standard and therefore does not satisfy the design requirement for a standards-based solution.