A customer uses VLANs for tenant network separation. However, they are not satisfied with the scalability limits of the setup. Which networking technology will help the service provider to overcome…

Question

Options

• Adata center bridging (DCB)
• BRDMA over Converged Ethernet (RoCE)
• Cnetwork virtualization generic routing encapsulation (NVGRE)
• Dremote direct memory access (RDMA)

• A
  10% (3)
• B
  16% (5)
• C
  71% (22)
• D
  3% (1)

Explanation

NVGRE solves the VLAN scalability problem because VLANs are limited to 4,096 unique IDs (12-bit field), which is insufficient for large multi-tenant environments. NVGRE encapsulates Layer 2 frames inside GRE tunnels and uses a 24-bit Virtual Subnet ID (VSID), supporting up to ~16 million virtual networks - a massive leap that enables true multi-tenant cloud-scale separation.

Why the distractors are wrong:

• A (DCB): Data Center Bridging addresses lossless Ethernet and QoS (flow control, priority queuing) - it has nothing to do with VLAN ID limits.
• B (RoCE): RDMA over Converged Ethernet enables low-latency memory transfers over Ethernet - it's a transport optimization, not a network segmentation solution.
• D (RDMA): Remote Direct Memory Access bypasses the OS for fast memory-to-memory transfers between hosts - again, a performance/latency technology, not a virtualization overlay.

Memory tip: Think "12 vs 24" - VLANs give you 12 bits (~4K), NVGRE gives you 24 bits (~16M). When the exam mentions tenant scale limits + VLANs, the answer is always the technology with the bigger ID space - NVGRE (or its close cousin VXLAN).

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