Author: Marcin Bała, MSc Eng., Chief Technology Officer
Published: May 2026 | Updated: May 2026 | Reading time: 9 minutes
Three Generations of 800G Architecture - What the Abbreviated Spec Doesn’t Tell You
The biggest mistake when buying 800G modules: treating "800G" as a homogeneous standard. In reality it covers three different generations of electrical architecture that coexist on the market today, each with different switch requirements.
Generation 1 (being phased out): 8 electrical lanes 100G PAM4, 8 optical lanes 100G PAM4. Mainly SR8 modules for multimode fiber. Available since 2021, now being phased out - do not order!
Generation 2 (2026 market standard): 8 electrical lanes 112G PAM4, 4 optical lanes 200G PAM4. This is the standard you buy today with DR4 (500 m SMF) and FR4 (2 km SMF) modules. Supported by Arista 7050X4, Cisco NCS 5500, and Juniper QFX10000. Full multi-vendor interoperability, IEEE 802.3df ratified.
Generation 3 (entering 2026): 4 electrical lanes 224G PAM4, 4 optical lanes 200G PAM4. Backwards compatible with Gen 2, but requires a switch with an ASIC supporting 224G SerDes for full performance. Limited availability.
When ordering 800G modules, always ask about the generation. Gen 2 is the standard, Gen 3 is entering the market and is not yet available in all models.
Full Specification: 800G DR4 Gen 2 vs 1.6T DR8
Parameter
800G DR4 Gen 2
1.6T DR8
Optical interface
4 × 200G PAM4 SMF
8 × 200G PAM4 SMF
Electrical interface
8 × 112G PAM4
8 × 200G PAM4
DR range
500 m SMF
500 m SMF
DSP node
5nm CMOS ✓
5nm → 3nm 2027
DSP power draw
15–17 W
20–30 W
LPO power draw
11–13 W
10–15 W
Form factor
OSFP / QSFP-DD800
OSFP-XD / OSFP224
Price Q1 2026
$700–900
$2,600–3,100
Cost per Gbps
$0.88–1.12/Gbps
$1.63–1.94/Gbps
IEEE standard
802.3df ✓ 2024
802.3dj draft Q1 2026
Interoperability
40 vendors OFC 2026
Not guaranteed
Lead time
2–8 weeks
8–20 weeks
DSP - Why It Matters More Than the Module Brand
The DSP (Digital Signal Processor) determines the module’s capabilities: range, LPO support, integration with network management systems, and compatibility with the host ASIC. You buy a module, but you are actually choosing a DSP ecosystem.
Broadcom Sian2
BCM57414
Supports: 800G and 1.6T LPO
Advantage: best energy efficiency
Availability: broad, Q1 2026
Low power draw
Marvell Orion
Supports: 800G and 800ZR+
ZR+ range: up to 2,000 km in 600G mode
Advantage: adaptive PCS modulation
Preferred for DCI
Cisco Acacia Porrima
Supports: 400ZR, 800ZR, ZR+
ZR+ range: up to 1,200 km
Advantage: native Cisco NSO integration
Cisco environments
Coherent Corp. DSP
Supports: 400ZR, 800ZR, ZR+
Range: up to 1,000 km
Advantage: broad partner ecosystem
Diversification
When ordering modules for a Polish data centre: always ask the integrator which DSP is in the module and whether it is compatible with your switch. This is the question to ask before placing the order, not after receiving the hardware.
Three 1.6T Architecture Variants - Critical for Cooling Design
The term "1.6T" covers three fundamentally different architectures with very different power draws and host requirements.
01
Full DSP — 20–30 W per port
DSP in the module — plug-and-play, per-port replacement in minutes. Does not require a special ASIC in the switch. The most expensive and most power-hungry option, but the simplest to deploy.
Sampling and early rollout Q1 2026
02
LPO/LRO — 10–15 W per port
DSP moved to the host ASIC. Requires a switch with an LPO-ready ASIC: Broadcom Sian2, Marvell Teralynx 10, Nvidia Spectrum-4. Reduces power draw by 30–40% vs full DSP.
Pilots at Nvidia and Meta Q1 2026
03
CPO (Co-Packaged Optics) — 5–7 W per 800G equivalent
Optical engine integrated directly into the switch ASIC. 65% energy saving vs pluggable. On failure you replace the entire switch — repair time: hours instead of minutes.
Not for enterprise DC in Poland 2026
Critical thermal information: 32 ports × 28 W = 896 W from optics alone per top-of-rack switch. 4 switches per row = 3,584 W. Requires a rear-door heat exchanger or liquid cooling as a minimum — this is not an option, it is a requirement. CAPEX cost of cooling retrofit: €20,000–40,000.
Infrastructure Requirements - What to Verify Before Ordering
800G Gen 2 modules work with any switch supporting CMIS 5.x and 8×112G PAM4. Confirmed in Poland: Arista 7050X4, Cisco NCS 5500, Juniper QFX10000, Nokia 7750 SR. 1.6T full DSP modules require a switch with an ASIC supporting 200G/lane electrical. Broadcom Tomahawk 6 or Marvell Teralynx 10. In practice this means replacing the switch. Devices with these ASICs become available from mid-2026.
EML laser shortage - the longest lead time in the project. Nvidia has reserved the production capacity of key 200G EML laser suppliers until 2027+. Lead time for non-Nvidia models can exceed 52 weeks for certain configurations. Order 3–6 months in advance, not one quarter before you need them.
5-Year TCO for 100 Ports - Full Calculation
Base option
800G OSFP DSP
CAPEX × 100$80,000
Energy / year€19,622
Energy 5 years€98,110
Cooling€0
Switch upgrade€0
~€89,400
5-year TCO · 100 ports
Best result
800G OSFP LPO
CAPEX × 100$60,000
Energy / year€14,717
Energy 5 years€73,585
Cooling€0
Switch upgrade€0
~€66,700
5-year TCO · 100 ports
Hyperscalers 50k+ GPU
1.6T OSFP DR8 DSP
CAPEX × 100$285,000
Energy / year€30,660
Energy 5 years€153,300
Cooling€25–40,000
Switch upgradeRequired
~€305,000
5-year TCO · 100 ports
The difference between 800G DSP and 1.6T DSP: over €215,000 per 100 ports over 5 years - without any additional business value for a DC below 50,000 GPU ports.
Decision Matrix - What to Recommend and When
Enterprise DC below 10,000 GPU ports: 800G DSP or LPO. No economic or technical justification for 1.6T. Negotiate the price - the market is dropping 10–15% per year.
Cloud and colo 10,000–50,000 ports: 800G LPO where the switch is LPO-ready, DSP where it is not. Pilot 1.6T on 1–2 links as a proof-of-concept.
AI cluster above 50,000 GPU: 1.6T conversation is justified - but only after verifying switch ASICs, cooling plan, and EML availability from a specific vendor.
New buildout with a 5+ year horizon: switches with 200G/lane electrical ASIC (TH6 or MT10), cooling ready for 30 W per port, 800G modules now. Infrastructure designed for 1.6T, 800G modules purchased today.
Metro and regional DCI below 120 km: 800ZR+ pluggable. Available now, prices falling - do not wait.
Ready to Talk About a Project?
We will go through your current switch stack, module generations, and expansion plan. We will tell you straight what to order, in what order, and how to design the infrastructure for 1.6T without replacing everything in two years.
FAQ — 800G vs 1.6T Technical Analysis
Gen 1 (being phased out) uses 8 electrical lanes at 100G PAM4 — worse thermal characteristics, do not order. Gen 2 (2026 market standard) uses 8 electrical lanes at 112G PAM4 and 4 optical lanes at 200G PAM4 — these are the DR4 and FR4 modules you buy today. Supported by Arista 7050X4, Cisco NCS 5500, and Juniper QFX10000. Gen 3 (entering 2026) uses 4 electrical lanes at 224G PAM4 — backwards compatible with Gen 2, but requires an ASIC supporting 224G SerDes for full performance. Always ask about the generation when ordering.
This is precisely the difference that requires a switch replacement when moving to 1.6T. 800G Gen 2 uses 8 electrical lanes at 112G PAM4. 1.6T DR8 requires 8 electrical lanes at 200G PAM4 — meaning the host ASIC must support 200G/lane: Broadcom Tomahawk 6 or Marvell Teralynx 10. Devices with these ASICs only become available from mid-2026. You cannot deploy 1.6T without replacing the switch — this is not a firmware issue.
The DSP determines range, LPO support, integration with management systems, and compatibility with the host ASIC. You buy a module, but you are actually choosing a DSP ecosystem. Broadcom Sian2 offers the best energy efficiency and LPO support. Marvell Orion provides ZR+ range up to 2,000 km for DCI. Cisco Acacia Porrima offers native integration with Cisco NSO. Coherent Corp. DSP is a solid alternative for vendor diversification. Before ordering, always ask the integrator which DSP is in the module and whether it is compatible with your switch.
Full DSP (20–30 W per port): plug-and-play, per-port replacement in minutes, no special ASIC required — but the most expensive and most power-hungry option. LPO/LRO (10–15 W per port): DSP moved to the host ASIC, 30–40% energy saving vs full DSP, requires a switch with an LPO-ready ASIC (Broadcom Sian2, Marvell Teralynx 10, Nvidia Spectrum-4). CPO (5–7 W per 800G equivalent): optics integrated directly into the switch ASIC, 65% energy saving vs pluggable, but on failure you replace the entire switch — not suitable for enterprise DC in Poland in 2026.
At PUE 1.4 and €0.10/kWh: 800G full DSP — ~€89,400 total ($80,000 CAPEX + €98,110 energy, no switch upgrade or cooling). 800G LPO — ~€66,700 — the best result on the market. 1.6T full DSP — ~€305,000 total ($285,000 CAPEX + €153,300 energy + €25–40,000 cooling + required switch upgrade). Difference between 800G DSP and 1.6T: over €215,000 per 100 ports over 5 years — without any additional business value for a DC below 50,000 GPU ports.
800G modules: 2–8 weeks. 1.6T modules: 8–20 weeks. But the real problem is 200G EML lasers — Nvidia has reserved the production capacity of key suppliers (Lumentum, Coherent Corp., Source Photonics) until 2027+. Lead time for non-Nvidia models can exceed 52 weeks for certain configurations. Order 3–6 months in advance — not one quarter before you need them. This is the longest lead time in the entire project — longer than switches or cabling.
The 1.6T conversation is justified for a GPU cluster above 50,000 cards where port density matters more than price. Before ordering, verify: (1) switch ASIC supports 200G/lane electrical — Broadcom Tomahawk 6 or Marvell Teralynx 10; (2) cooling ready for 30 W per port — rear-door heat exchanger or liquid cooling is a requirement, not an option; (3) the vendor will confirm compliance with the final IEEE 802.3dj standard once approved. For enterprise DC below 10,000 GPU ports: no economic or technical justification for 1.6T in 2026.
For a new buildout with a 5+ year horizon: choose switches with 200G/lane electrical ASIC (Broadcom Tomahawk 6 or Marvell Teralynx 10), plan cooling ready for 30 W per port, and buy 800G modules now. The 2027–2028 migration to 1.6T will then simply mean swapping modules in existing ports — evolution, not revolution. Organisations that buy switches today without thinking about 1.6T will have to replace the entire infrastructure when moving to the higher standard.
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