Sai Natarajan of Cisco presents the Nexus One architecture and how it helps enterprises modernize existing data center fabrics for AI. The session covers Silicon One programmability, new 800G spine and high-density 100G top-of-rack switches, smart switches with embedded security, 400G BiDi optics, and coexistence across ACI, NX-OS, HyperFabric, and SONiC. Natarajan, who leads products for Cisco’s data center networking business, delivered the opening segment at Networking Field Day 41, ahead of a deep dive and demo from Takuya Kishida. He framed modernization around three pillars: AI-ready fabrics where existing and AI workloads coexist, security that covers east-west traffic and AI-driven attacks, and unified, agentic operations.

Natarajan described Nexus One as an architecture rather than a product, comparable in purpose to ACI, that integrates Cisco silicon, systems, optics, software, and operating models while keeping each layer composable. Silicon One’s P4 programmability lets Cisco add hardware-accelerated features as AI requirements evolve. New hardware includes a 3RU spine with 64 ports of 800G on P200 silicon in OSFP and QSFP variants, and a 48-port 100G top-of-rack switch with eight 400G uplinks on 12.8 Tbps Cloud Scale silicon, shipping in Q1 of next calendar year. Smart switches pair Silicon One with AMD DPUs running HyperShield, generally available since August, redirecting up to 800G of traffic at line rate for stateful firewalling. Cisco is also rebuilding popular leaf and spine switches on E100 silicon, adding hardware secure boot for post-quantum readiness, moving to DDR5 memory, and introducing 36-port 800G modular line cards.

The through line was investment protection. HyperFabric now extends to Nexus 9000 switches, and Nexus One connects to Cisco Cloud Control through MCP servers in the Nexus Dashboard and HyperFabric controllers. The 400G BiDi optics use two 100G wavelengths in each direction so customers can upgrade over existing fiber, a benefit delegates reinforced when describing the cost of replacing an entire fiber plant. Natarajan explained that SONiC is supported on select platforms because Cisco prefers to meet customers where they want to go, and since the hardware stays the same, a customer that tries SONiC can return to NX-OS, ACI, or HyperFabric without replacing a single switch.

Presented by Sai Natarajan, Senior Director. Recorded live at Networking Field Day 41 in Santa Clara, CA on October 8, 2026. Watch the entire presentation at https://techfieldday.com/appearance/cisco-data-center-presents-at-networking-field-day-41/ or visit https://techfieldday.com/event/nfd41/ or https://Cisco.com/ for more information.