Broadcom Tomahawk 6 – Davisson (TH6-Davisson)

Provenance note: Fills the KB's flagged gap — "Broadcom CPO (Tomahawk 6 / Davisson)... is shipping 3rd-gen CPO... developing 4th-gen; missing from entities" (frontier.md, prior to this ingest).

Abstract

Broadcom's third-generation co-packaged-optics Ethernet switch, shipping since October 2025 — the industry's first 102.4 Tbps CPO switch, doubling the bandwidth of any prior CPO product.

Key Contributions / Findings

• Part number: BCM78919. Generation: Tomahawk 6, successor to the Tomahawk 5-based "Bailly" CPO switch already implicitly covered via the KB's broader CPO timeline.
• Bandwidth: 102.4 Tbps total, via 64 ports of 1.6 TbE (Terabit Ethernet).
• SerDes: 64 "Condor" 3nm SerDes cores, each with eight 212.5 Gb/s PAM4 lanes.
• Optical engines: 16 "Davisson DR" optical engines (6.4 Tbps each), built on TSMC's COUPE (Compact Universal Photonic Engine) platform — the same foundry platform the KB already tracks via the Alchip/Ayar Labs demo (tsmc-coupe-silicon-photonics.md).
• Power: ~70% lower power consumption vs. traditional pluggable-optics solutions, from eliminating high-speed/high-power electrical signaling between the switch package and optical cages.
• Serviceability differentiator: pluggable, field-replaceable laser modules — addressing the classic CPO objection (a single laser failure normally means scrapping the whole co-packaged unit).
• Target use case: large AI clusters needing high-density connectivity while preserving power budget for accelerators rather than networking.

Why It Matters (lens: optical-computing — co-packaged optics, near-term / competitive positioning)

Closes a named entity gap and gives the KB its first head-to-head data point between the two switch-silicon incumbents committing to CPO: Broadcom (102.4 Tbps, shipping now, TSMC COUPE, serviceable lasers) vs. NVIDIA Spectrum-X/Quantum-X Photonics (up to 400 Tbps, guided to 2H 2026, own ecosystem). The field-replaceable-laser design is itself a datapoint against the LENS's forbidden pattern of ignoring thermal/reliability management — Broadcom is explicitly engineering around the reliability failure mode that skeptics raise against monolithic CPO.

Limitations

• No specific executive quotes captured in the sources retrieved (press-release headline + a technical trade-press writeup, not the full official release body).
• No independent power-consumption verification — the 70% figure is Broadcom's own claim.

Source: Broadcom Tomahawk 6 – Davisson — Broadcom Inc., October 17, 2025; technical detail cross-checked against ServeTheHome's writeup.