NVIDIA Updated NCP-AIN Exam Questions and Answers by damon

Comprehensive and Detailed 150 to 250 words of Explanation From NVIDIA AI Networking Topics:

The correct answer is B. nv set qos roce enable on . In NVIDIA Cumulus Linux, RoCE configuration is managed under the QoS hierarchy in NVUE because RoCE depends on lossless Ethernet behavior, priority flow control, congestion management, and related quality-of-service mechanisms. NVIDIA’s official Cumulus Linux documentation shows that the RoCE feature is configured through nv set qos roce , and in newer command references this appears explicitly as nv set qos roce enable on|off . This confirms both the command structure and the ordering of the keywords: nv set → qos → roce → enable on .

The other options are incorrect because they do not follow valid NVUE syntax. NVIDIA documents NVUE commands in a strict object-based order, where the top-level feature group comes immediately after nv set . Since RoCE is implemented as part of the QoS framework, qos must appear before roce . Commands such as nv set roce qos enable on , nv qos roce enable on , and nv roce qos enable on do not match the official NVIDIA command model. Therefore, for enabling RoCE on a Cumulus switch in an NVIDIA AI networking environment, the verified command is nv set qos roce enable on .

The ibnetdiscover utility is used to perform InfiniBand subnet discovery and outputs a human-readable topology file. GUIDs, node types, and port numbers are displayed, as well as port LIDs and node descriptions. All nodes and links are displayed, providing a full topology. This utility can also be used to list the current connected nodes. The output is printed to the standard output unless a topology file is specified.​

InfiniBand is a high-performance, low-latency interconnect technology used in AI and HPC data centers, particularly for east-west traffic between compute nodes in large-scale fabrics. Ensuring seamless data flow requires tools to troubleshoot and monitor the network, including the ability to trace and discover network paths between nodes. The question asks for the specific tool used to trace and discover paths in an InfiniBand fabric, which is a key task in InfiniBand troubleshooting.

According to NVIDIA’s official InfiniBand documentation, the ibnetdiscover tool is designed to discover and map the topology of an InfiniBand fabric, including the paths between nodes. It scans the fabric, queries the subnet manager, and generates a topology map that details the connections between switches, Host Channel Adapters (HCAs), and other devices. This tool is essential for verifying connectivity, identifying routing paths, and troubleshooting issues like misconfigured routes or link failures in large-scale InfiniBand fabrics.

Exact Extract from NVIDIA Documentation:

“The ibnetdiscover tool is used to discover the InfiniBand fabric topology and generate a map of the network. It queries the subnet manager to retrieve information about all nodes, switches, and links in the fabric, providing a detailed view of the paths between nodes. This tool is critical for troubleshooting connectivity issues and ensuring proper routing in InfiniBand networks.”

— NVIDIA InfiniBand Networking Guide

This extract confirms that ibnetdiscover is the correct tool for discovering network paths in an InfiniBand east-west fabric. It provides a comprehensive view of the fabric’s topology, enabling administrators to trace paths between compute nodes and ensure seamless data flow.

In NVIDIA Spectrum-X, congestion is evaluated based on egress queue loads. Spectrum-4 switches assess the load on each egress queue and select the port with the minimal load for packet transmission. This approach ensures that all ports are well-balanced, optimizing network performance and minimizing congestion.

EVPN Multi-homing enables active-active redundancy without inter-switch links by using overlay routing over VXLAN and distributed control plane using BGP EVPN.

From the official NVIDIA Cumulus Linux EVPN Multihoming Documentation :

"EVPN multihoming allows multiple Top-of-Rack (ToR) switches to connect to the same server while maintaining full layer-2 redundancy without the need for inter-switch links or traditional MLAG configuration."

Key benefits:

Simplified topology (no ISL/peer-link needed)

BGP-based control plane

Fast convergence

Active-active links per host NIC

Incorrect Options:

MLAG requires ISL between switches and peer-link configuration.

VSS (Virtual Switching System) is a Cisco term, not supported in NVIDIA networking.