Cisco Nexus vs Juniper QFX: Data Center Comparison

Nexus vs QFX: Choosing a Data Center Fabric

For a modern spine-leaf data center in 2026, the choice comes down to Cisco Nexus and Juniper QFX. Both support EVPN-VXLAN, 25G/100G/400G, and cut-through latency <1µs. The key differences are automation (Cisco ACI/NDFC vs Juniper Apstra), price, and latency.

Equivalent Models

• Leaf with 48× 25G + 6× 100G: Nexus 93180YC-FX (€15K) vs QFX5120-48Y (€13K). QFX is 13% less expensive.
• Spine with 32× 100G: Nexus 9336C-FX2 (€20K) vs QFX5120-32C (€17K). QFX is 15% less expensive.
• 400G spine: Nexus 9332D-GX2B (€50K) vs QFX5130-32CD (€44K). QFX is 12% less expensive.

Latency and Buffer Capacity

• Nexus 93180YC-FX: 1µs latency, 40MB buffer. QFX5120-48Y: 550ns, 32MB. QFX delivers lower latency, while Nexus provides greater buffer capacity, which is important for bursty workloads.
• Nexus 9336C-FX2: 1µs, 40MB. QFX5120-32C: 800ns, 32MB.

Automation: ACI vs Apstra

Cisco ACI (Application Centric Infrastructure)

• 3 mandatory APIC controllers (~€80K).
• Intent-based approach using EPGs, contracts, and VRFs.
• Mature solution (since 2014), deployed in most large French data centers.
• Steep learning curve (CCNP DC + ACI-specific certification).
• Cisco lock-in: works ONLY with Nexus in ACI mode.

Cisco NDFC (Nexus Dashboard Fabric Controller)

• Cisco-only orchestration for conventional EVPN-VXLAN fabrics (non-ACI).
• More lightweight than ACI, but still Cisco-only.

Juniper Apstra

• Multi-vendor: manages Juniper QFX + Cisco Nexus + Arista EOS + SONiC + NVIDIA Cumulus.
• Intent-based and blueprint-driven.
• Per-device licensing.
• Unique advantage: support for a multi-vendor fabric or a progressive Cisco → Juniper migration without changing tools.

Recommended Use Cases

• Existing Cisco data center with ACI: remain on Nexus because migration would be too costly.
• New data center focused on automation: QFX + Apstra for a more agile, multi-vendor environment.
• Very large data center (>100 racks): Nexus 9800 or ACI at very large scale.
• Mid-sized data center focused on TCO: QFX5120 + Apstra, with 15% lower hardware costs and Apstra licensing that is often less expensive than ACI.
• Carrier / ISP: QFX + MX Junos for routing and data center consistency.

5-Year TCO for 50 Leafs + 8 Spines

• Cisco: 50× 93180YC-FX (€750K) + 8× 9336C-FX2 (€160K) + ACI controllers (€80K) + 5-year SmartNet support at ~15%/year = ~€1.6M.
• Juniper: 50× QFX5120-48Y (€650K) + 8× QFX5120-32C (€136K) + Apstra licenses (~€50K) + 5-year JTAC support at ~12%/year = ~€1.1M.
• Difference: €500,000 in Juniper savings over 5 years.

OPTINOC distributes Nexus and QFX with manufacturer-backed warranties. Comparative data center architecture assessments are available upon request.