Why Modern Data Center Switches Are the Backbone of AI Scaling

1. Main Classification of Switches

Switches can be categorized by application scenario (campus vs. data‑center), network layer (access, aggregation, core), management type (unmanaged, web‑managed, fully managed), OSI layer (Layer‑2, Layer‑3), port speed (100 Mb, 1 Gb, 10 Gb, multi‑rate) and chassis form factor (box vs. chassis).

2. Switch Chip and Key Metrics

Ethernet switches consist of a chip, PCB, optical components, connectors, passive components, chassis, power supply and fans. The chip includes an Ethernet switching ASIC, CPU, PHY and CPLD/FPGA, with the ASIC and CPU being the core. Switching performance depends on back‑plane bandwidth, packet‑forwarding rate, switching capacity, port speed and port density. When back‑plane bandwidth ≥ switching capacity (port count × port speed × 2), line‑rate, non‑blocking forwarding is achieved.

3. Switch Development and Technology Evolution

As AI models and data volumes increase, distributed training relies on high‑performance switches to keep tail latency low. Optical‑to‑Electrical‑to‑Optical (OEO) packet‑circuit switches require optical‑electrical conversion, while Optical Circuit Switches (OCS) provide full‑optical paths, reducing conversion overhead. Lightmatter’s Passage uses waveguide‑based photonic interconnects for AI‑scale bandwidth. Google’s Jupiter architecture integrates OCS to replace electrical EPS, cutting conversion steps and improving scalability.

4. Key Technologies and Standards

RDMA (Remote Direct Memory Access) enables high‑throughput, low‑latency communication by bypassing the OS kernel. Main implementations are InfiniBand, iWARP and RoCE (v1/v2). InfiniBand offers the lowest latency but higher cost; RoCEv2 runs over Ethernet with UDP/IP, providing better scalability and lower cost. Both dramatically reduce end‑to‑end latency compared with TCP/IP (e.g., 50 µs → 5 µs RoCE, 2 µs InfiniBand). Ethernet continues to dominate AI‑back‑end networks, with forecasts of over $100 billion spend on AI‑oriented Ethernet switches by 2029.