A company would like to distribute a virtual machine (VM) hosting cluster between three data centers with the capability to move VMs between sites. The connectivity between data centers is IP only and

Question

Options

• AAToM
• BL2TPv3
• COTV
• DVPLS

• A
  11% (3)
• B
  4% (1)
• C
  81% (22)
• D
  4% (1)

Explanation

OTV (Overlay Transport Virtualization) is the correct choice because it was purpose-built for data center interconnect (DCI) scenarios exactly like this one - it extends Layer 2 VLANs across an IP-only WAN, enabling VM live migration (vMotion) between sites while VMs retain their MAC and IP addresses. It supports multipoint topologies natively, so all three data centers participate without a mesh of point-to-point tunnels.

Why the others are wrong:

• AToM (A) requires an MPLS core, not an IP-only WAN - ruled out by the scenario constraint.
• L2TPv3 (B) can tunnel L2 over IP, but it's a point-to-point technology; connecting three sites requires multiple manual tunnels, and it lacks OTV's multicast optimization and loop-prevention features built for DCI.
• VPLS (D) also requires MPLS in the service provider core to build the multipoint L2 VPN - again incompatible with an IP-only WAN.

Memory tip: Associate OTV with "Over-The-Vlan for vMotion" - whenever a question mentions VM mobility + multiple data centers + IP WAN (no MPLS), OTV is the answer. If you see MPLS in the constraints, then VPLS or AToM become candidates.

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