News
SOLUTION
As AI training clusters push DCI bandwidth past 100 Tbps, the choice between 800G ZR+ and 400G CFP2-DCO is not one-size-fits-all. Apex delivers a hybrid coherent optics architecture that optimizes cost-per-bit on metro rings while preserving reach on long-haul backbone routes.
36PORTS PER RU
2,000+ kmMAX COHERENT REACH
30%PER-BIT POWER SAVED
Hyperscale data centers and AI training clusters are pushing east-west traffic past 100 Tbps. DCI links connecting colocation sites, metro rings, and disaster-recovery pairs face four compounding pressures:
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Metro rings (50-200 km) need density; long-haul spans (1,000+ km) need reach. No single coherent optic does both optimally.
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400G DCO modules consume ~24W each. At 16+ modules per site, DCI power rivals switch silicon.
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Running a separate transponder shelf for coherent line cards adds O-E-O conversions, latency, and rack space.
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Migrating from 10G/100G DWDM to 400G/800G coherent without a forklift upgrade calls for a flexible architecture.
THE INDUSTRY SHIFT
800G ZR+ in QSFP-DD plugs directly into switch cages — no transponder shelf. For sub-800 km metro and regional links, it delivers 2x throughput at 30% lower per-bit power vs. 400G DCO. Beyond 1,200 km, 400G CFP2-DCO's field-hardened reach keeps it relevant.
Apex proposes a hybrid coherent fabric — 800G ZR+ for metro aggregation, 400G CFP2-DCO for long-haul backbone — unified under a common DWDM and amplification layer:
┌───────────────────────────────────────────────────────┐
│ Tier 1: Metro Ring (50–200 km) │
│ 800G QSFP-DD ZR+ → plugged into spine switch cage │
│ No transponder shelf. 36 ports per RU. 120 Gbaud PCS. │
├───────────────────────────────────────────────────────┤
│ Tier 2: DWDM Multiplexing (Passive) │
│ 40-CH DWDM MUX/DEMUX (C-band, 100 GHz grid) │
│ Multiplex ZR+ and DCO wavelengths onto single fiber pair │
├───────────────────────────────────────────────────────┤
│ Tier 3: Amplification (Active) │
│ EDFA Booster + Pre-Amplifier │
│ Compensate span loss. Extend reach to 2,000+ km. │
├───────────────────────────────────────────────────────┤
│ Tier 4: Long-Haul Backbone (1,000–3,000+ km) │
│ 400G CFP2-DCO → plugged into line-system or switch │
│ Field-hardened reach. Flexible 100-400G fallback modes. │
└───────────────────────────────────────────────────────┘
| TIER | PRODUCT | FORM FACTOR | REACH | TYPICAL QTY |
| Metro | 800G QSFP-DD ZR+ | QSFP-DD | 500–2,000+ km | 8–16 per site |
| Long-Haul | 400G CFP2-DCO | CFP2 | 1,000–3,000+ km | 4–8 per span |
| Mux | DWDM MUX/DEMUX (40-CH) | 1RU passive | N/A | 1 pair per site |
| Amp | EDFA Optical Amplifier | 1RU active | N/A | 2 per span direction |
| Monitor | Optical Channel Monitor (OCM) | 1RU | N/A | 1 per site |
36
QSFP-DD ports per RU vs. 16 with CFP2
30%
Lower per-bit power vs. all-400G-DCO fabric
0
Transponder shelves eliminated on metro rings
40λ
Per fiber pair with 100 GHz DWDM grid
| CAPABILITY | WHAT IT MEANS FOR YOUR DCI NETWORK |
| Hybrid ZR+/DCO portfolio | Single supplier for both 800G ZR+ and 400G DCO — one qualification cycle, one sparing pool. |
| Pre-tested with DWDM mux | ZR+ modules ship with insertion loss budget verified against Apex 40-CH MUX/DEMUX — guaranteed channel power. |
| Telcordia-qualified | Both ZR+ and DCO pass GR-468 reliability testing. Link budgets hold over temperature and over time. |
| Flexible modulation fallback | ZR+ supports 400G/600G fallback modes on impaired fibers. DCO adjusts from 100G to 400G per wavelength. |
| CMIS-compliant telemetry | Real-time OSNR, pre-FEC BER, chromatic dispersion, and DGD monitoring via standard CMIS registers. |
A cloud provider connecting three colocation sites across a 150 km metro ring, each site currently at 1.6 Tbps. As AI training clusters demand more bandwidth, the provider must double to 3.2 Tbps:
| PARAMETER | ALL-400G DCO BASELINE | APEX HYBRID SOLUTION | DELTA |
| Modules per site | 16 × 400G CFP2-DCO | 8 × 800G QSFP-DD ZR+ | −50% |
| Rack space (DCI layer) | 8 RU (2 shelves) | 2 RU (no shelves) | −6 RU |
| Per-site DCI power | ~400 W | ~220 W | −180 W |
| Front-panel client ports freed | 0 | 8 × QSFP-DD cages | +8 ports |
| O-E-O conversions eliminated | 2 per direction | 0 | −4 per span |
| DWDM fiber pairs | 2 | 1 (40λ) | −50% fiber |
BOTTOM LINE
800G ZR+ in QSFP-DD eliminates transponder shelves on sub-800 km spans, cutting rack space by 75% and power by 45%. Reserve 400G CFP2-DCO for the long-haul backbone where reach matters more than density. Apex supplies both under one qualification and one sparing pool.
Our coherent optics engineers will model your spans, recommend a ZR+/DCO hybrid architecture, and deliver a full BOM with span budgets — typically within 48 hours.
EMAIL[email protected]
WHATSAPP / PHONE+852 9821 3834
WEBSITEapexallinone.com
