> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.nvidia.com/dsx/llms.txt.
> For full documentation content, see https://docs.nvidia.com/dsx/llms-full.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/dsx/_mcp/server.

# Network Transport and Fabric Visibility

## Network Transport and Fabric Visibility

#### Backend Switch Fabric API

The purpose of this API is to expose sufficient information about the cluster’s network topology to enable efficient scheduling, placement, and optimization of multi-node GPU workloads. Understanding the network hierarchy between compute instances and switches, as well as both intra- and inter-node NVLink domains, is essential for minimizing communication latency and maximizing throughput.  Thus, this applies to North-South, East-West, and NVLink networks (not MGMT).  See the appendix for a DGXC recommended reference implementation.

| Req ID    | Test Details [(Legend)](/dsx/ncp/nvidia-requirements-for-ai-clouds/appendix#test-legend) | Requirement Area          | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| :-------- | :--------------------------------------------------------------------------------------- | :------------------------ | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **NET01** | INFO                                                                                     | Backend Switch Fabric API | For each compute node, the API must provide visibility into the backend network switches connecting the node to the core. **Identification:** Each switch must be identified by a unique, stable identifier. A "switch" may represent a physical switch or a logical connectivity domain. **Structure:** API may be gRPC or REST. Response structure may include multiple nodes (pagination expected). **Topology:** Switch info can be returned as an ordered array of IDs (e.g., leaf, spine, core) or separate fields for each tier |
| **NET02** | INFO                                                                                     | NVLink Domain API         | **Requirement:** For compute nodes supporting NVLink (e.g., GB200, GB300, Vera Rubin), the API shall return the unique identifier of the NVLink domain associated with each node. **Implementation:** Can be a separate API method or part of the Backend Switch Fabric API.                                                                                                                                                                                                                                                           |

###