NCA NVIDIA Networking & Interconnects 3

Question 1

What is the key advantage of NVLink Switch System (NVL72) compared to PCIe-based GPU interconnects?

Accepted Answer

Higher bandwidth and lower latency for all-to-all GPU communication

Answer

NVLink Switch System provides terabits-per-second all-to-all bandwidth between GPUs with microsecond latency, far exceeding PCIe.

Question 2

In InfiniBand networking, what is a 'fat-tree' topology primarily designed to achieve?

Accepted Answer

Provide non-blocking full bisection bandwidth

Answer

Fat-tree topologies are designed to provide full bisection bandwidth, ensuring no bottleneck regardless of traffic pattern.

Question 3

Which NVIDIA technology allows network adapters to process Ethernet frames and perform RDMA operations simultaneously on the same port?

Accepted Answer

RoCE (RDMA over Converged Ethernet)

Answer

RoCE enables RDMA semantics over standard Ethernet, allowing the same physical port to handle both standard Ethernet and RDMA traffic.

Question 4

What is the purpose of Priority Flow Control (PFC) in a RoCE deployment?

Accepted Answer

Prevent packet loss on lossless queues required for RDMA

Answer

PFC creates lossless Ethernet queues by sending pause frames when buffers fill, which is required for reliable RDMA operation.

Question 5

How many GPUs can be directly interconnected in a single NVLink domain using NVIDIA's H100 SXM platform?

Accepted Answer

8 GPUs

Answer

H100 SXM servers connect 8 GPUs within a single NVLink domain using NVSwitch chips for all-to-all connectivity.

(NCA) NVIDIA-Certified Associate Practice Test