InfiniBand is a high-performance computing (HPC) interconnect that provides significantly higher throughput and lower latency than standard Ethernet. For distributed AI training, where frequent and large-volume gradient exchanges occur between nodes, network performance is critical. InfiniBand utilizes Remote Direct Memory Access (RDMA), which allows GPUs on different nodes to communicate directly, bypassing the CPU and kernel network stack. This minimizes communication overhead and latency, preventing GPUs from idling while waiting for data, thereby directly addressing the performance bottleneck in multi-node training scenarios.

A. Increasing job replicas scales out the number of independent training instances but does not improve the communication performance within a single, distributed training job.

B. While jumbo frames can slightly reduce packet overhead on Ethernet, this interconnect still has fundamentally higher latency and lower bandwidth compared to InfiniBand for HPC workloads.

C. A dedicated storage network optimizes the I/O for loading datasets from storage, not the inter-node, inter-GPU communication required for the training algorithm's synchronization steps.

1. NVIDIA Corporation. (2020). NVIDIA DGX A100 System Architecture Whitepaper.

Reference: Page 13, Section "Networking for Scale-Out".

Quote: "For scaling out, the DGX A100 system has eight single-port Mellanox ConnectX-6 VPI HDR InfiniBand adapters... These provide 200 Gb/s of bandwidth per adapter for clustering. This massive bandwidth is required to feed the multi-GPU training jobs that run on DGX A100." This document establishes InfiniBand as the standard, high-performance interconnect for scaling out NVIDIA's flagship AI systems.

2. NVIDIA Developer Documentation. (2023). NVIDIA Collective Communication Library (NCCL) Documentation.

Reference: Introduction / Overview Section.

Content: The documentation states that NCCL is "optimized to achieve high bandwidth and low latency... over NVIDIA Mellanox InfiniBand and Ethernet networking for multi-node." This confirms that the core library for distributed training is specifically optimized for high-speed interconnects like InfiniBand.

3. Sato, K., et al. (2021). Demystifying the Performance of HPC Cloud for Deep Learning. 2021 IEEE International Parallel and Distributed Processing Symposium Workshops (IPDPSW).

Reference: Section IV-B, "Inter-node Communication".

DOI: https://doi.org/10.1109/IPDPSW52791.2021.00090

Content: The study analyzes communication performance for deep learning and notes that interconnects supporting RDMA, such as InfiniBand, provide significantly higher performance for distributed training by reducing communication overhead compared to traditional TCP/IP over Ethernet.