Layer 3 — Networking & interconnect

Position in the die→grid hierarchy: inside the server.

How chips, servers and sites talk to each other: the scale-up fabric inside a rack, the switch ASICs and systems of the scale-out network, the optical transceivers and copper cables between them, and the fiber and coherent optics linking buildings and campuses.

Parts in this layer

• 3.01 Scale-up fabric (GPU-to-GPU inside the rack/pod) · 6 companies
  The fabric linking GPUs to each other inside a single rack or pod, separate from the switching fabric that connects racks to each other.
• 3.02 Scale-out switch ASICs · 5 companies
  The switch ASICs that route traffic between racks and pods, distinct from the scale-up fabric inside a single rack.
• 3.03 Switch systems & white-box ODMs · 13 companies
  The physical switches — built by branded vendors and white-box ODMs — that house scale-out switch ASICs and connect racks into a cluster fabric.
• 3.04 Optical transceivers (400G / 800G / 1.6T) · 15 companies
  Pluggable optical modules that convert electrical signals to light for transmission over fiber between switches and servers, sold at 400G, 800G, and 1.6T speeds.
• 3.05 Optics contract manufacturing · 5 companies
  Contract manufacturers that assemble and test optical transceivers on behalf of module brands and switch vendors.
• 3.06 Lasers (EML, CW/DFB, VCSEL) · 8 companies
  The laser sources — EML, CW/DFB, and VCSEL types — that generate the light signal inside optical transceivers and co-packaged optics.
• 3.07 Optical DSPs, drivers, TIAs · 7 companies
  The signal-processing silicon inside optical modules — DSPs plus the drivers and TIAs that condition the electrical signal on either side of the laser and photodetector.
• 3.08 Silicon photonics & co-packaged optics (CPO) · 18 companies
  An approach that integrates optical components directly onto or next to the switch or GPU package, replacing some pluggable transceivers with light routed closer to the silicon.
• 3.09 Copper: DAC / ACC / AEC cables · 13 companies
  High-speed copper cable assemblies — DAC, ACC, and AEC types — that link GPUs, NICs, and switches over short distances as a lower-cost alternative to optical transceivers.
• 3.10 NVLink copper spine / backplane cartridges · 5 companies
  The copper cable assemblies and backplane cartridges that physically wire the scale-up fabric together inside a rack, most visible in Nvidia's NVL72 architecture.
• 3.11 Fiber, connectors, structured cabling · 14 companies
  The fiber optic cable, connectors, and structured cabling that carry optical signals between transceivers across a data hall or campus.
• 3.12 DCI / coherent optics (campus-to-campus, metro) · 9 companies
  Coherent optical systems that carry data center interconnect (DCI) traffic between buildings on a campus or between metro sites, distinct from the shorter-reach optics inside a data hall.
• 3.13 Timing & telemetry silicon · 5 companies
  Precision timing and telemetry chips that synchronize clocks and monitor signal integrity across the network fabric.

Public plays in this layer

Listed companies with the most part placements in layer 3. Placement count is breadth, not revenue exposure.