News
SOLUTION
Brownfield data centers running 400G QSFP56/QSFP-DD fabrics need a practical upgrade path — not a forklift. Apex delivers a phased migration strategy using backward-compatible 800G QSFP-DD optics, hybrid-speed leaf-spine topologies, and zero-touch transceiver swaps.
50%PORT COUNT REDUCTION
3MIGRATION PHASES
0FORKLIFT UPGRADES
Operators of 400G data centers face a difficult upgrade decision when AI workloads demand more bandwidth:
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Existing 400G switches use QSFP-DD cages. Replacing switches to support OSFP means a complete rip-and-replace.
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Mixing 400G and 800G optics in the same fabric can cause FEC mismatch, link flap, and unpredictable BER floors.
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Operators can't upgrade every rack at once. They need a per-pod migration path that respects CapEx cycles.
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800G SR8 needs different MPO polarity than 400G SR4. Existing fiber plant must be validated before migration.
THE CORE INSIGHT
QSFP-DD cages support both 400G and 800G optics natively. The migration is not a hardware problem — it is a planning, qualification, and phasing problem. Apex provides pre-tested optics with guaranteed backward compatibility so you upgrade at your pace.
1
Replace spine 400G transceivers with 800G QSFP-DD FR4/DR8. Spine ASICs support 800G natively. Leaves stay at 400G — spines auto-negotiate down per port. Zero leaf changes.
2
Upgrade leaf switches pod-by-pod to 800G QSFP-DD. GPU racks get 800G SR8/DR8 first. General-compute racks stay at 400G until next budget cycle. Hybrid fabric runs stable.
3
All leaf and spine ports at 800G. Deploy 800G ZR+ coherent for DCI links. End state: 2x bandwidth density, 50% fewer ports, 30% lower per-bit power vs. all-400G baseline.
| PHASE | PRODUCT | FORM FACTOR | REACH | TYPICAL QTY |
| 1 | 800G QSFP-DD FR4 | QSFP-DD | 2 km SMF | 32–64 |
| 1 | 800G QSFP-DD DR8 | QSFP-DD | 500 m SMF | 64–128 |
| 2 | 800G QSFP-DD SR8 | QSFP-DD | 100 m OM4 | 128–256 |
| 2 | 800G Active Optical Cable | QSFP-DD AOC | 3–30 m | 64–128 |
| 3 | 800G QSFP-DD ZR+ | QSFP-DD | 500–2,000+ km | 8–16 |
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Switch replacements required — QSFP-DD backward compatible
18 kW
Interconnect power saved per 10K-GPU pod at full 800G
50%
Fewer ports vs. all-400G fabric at equivalent bandwidth
3yr
Typical phased migration timeline, pod by pod
| CAPABILITY | WHY APEX |
| QSFP-DD backward compatible | Every Apex 800G QSFP-DD module auto-negotiates to 400G, 200G, and 100G lane speeds — plug into any QSFP-DD cage. |
| Pre-tested hybrid fabric | Apex validates 400G/800G mixed fabrics on Broadcom Tomahawk 5, Cisco Silicon One, and NVIDIA Spectrum-4 — no FEC mismatch. |
| Fiber audit tool | Free MPO polarity and insertion loss audit checklist for your existing fiber plant before migration. |
| Same-day swap inventory | All 800G modules ship from stock. Replace 400G optics in-place — no cage reconfiguration. |
Our migration engineers will audit your fabric topology, recommend a phased plan, and deliver a per-pod BOM with fiber compatibility checklist — typically within 48 hours.
EMAIL[email protected]
WHATSAPP / PHONE+852 9821 3834
WEBSITEapexallinone.com
