Celestica VP Tareq Bustami and Broadcom Head of Software Products Hasan Siraj presented at OCP Global Summit 2025 on the evolution of AI networking from early hyperscaler pain points to the industry's first 100 terabit switch. The session announced Broadcom's Tomahawk 6 (sampling June 2025, production early 2026), the Thor Ultra 800G NIC, and Celestica's DS6000/DS6001 switch family, all targeting 128K-GPU two-tier cluster topologies with over 40% power and optics savings vs. three-tier designs. The session also announced the OCP Ethernet for Scale-up Networking (ESUN) work stream as the industry consensus path for open AI scale-up interconnects, complementing the Ultra Ethernet Consortium's scale-out work.

Key Takeaways

• Broadcom's Tomahawk 6 is the world's first 100 terabit non-blocking switch ASIC (2,355B transistors, 102.4Tbps), began sampling June 2025, with production deployment starting early 2026; it is the only silicon that enables a two-tier topology for 128K-GPU clusters.
• A two-tier Tomahawk 6 topology achieves over 40% reduction in power, latency, and optics compared to a three-tier topology using prior-generation 51T switches, simplifying load balancing and congestion management.
• Celestica's DS6000 (3U air-cooled) and DS6001 (2U hybrid liquid-cooled) switches deliver 102.4Tbps with 64x 1.6TbE OSFP ports, 224G SerDes, and flexible port speeds (50–800GbE), running SONiC with OCP-standard security (PFR/DCSCM).
• The OCP Ethernet for Scale-up Networking (ESUN) work stream was launched at OCP 2025 with 12 founding members, establishing Ethernet (not proprietary protocols) as the consensus approach for AI scale-up networking.
• AI clusters of 100,000–150,000 XPUs are deploying today; a supercluster of 1 million XPUs is predicted within 3–5 years, requiring massive networking capacity additions (125–150 megawatts over 5 years).
• Co-packaged optics (CPO) is progressing, with Meta publishing reliability data; the near-term target deployment is scale-out, with scale-up identified as the longer-term killer application.
• Tomahawk 6 chiplets dissipate nearly 2kW each (GPU-class power), forcing Celestica to adopt 50-layer PCBs (few suppliers worldwide) and transition all factories to liquid cooling by 2026 under OV3 standards.
• Thor Ultra (BCM57708) is the industry's first 800G NIC, fully UEC-compliant (multipathing, OOO placement, selective retransmit, congestion control), interoperating with any switch vendor with zero feature degradation.