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[802.3_50G] 200GbE will be Different and Lower Cost/bit than 400GbE



I wanted to comment on some of the presentations that are coming out against 200GbE in the possibly final days of the NGOATH Study Group. 


As I showed in kipp_50GE_NGOATH_01_0116.pdf, 200GbE can be designed for low cost QSFP implementations from the start.  This makes 200GbE applicable to the low cost / high volume switch market while 400GbE will be suited for the high cost/ low volume router market.  200GbE will be a continuation of the successful, high volume progression from 40GbE QSFP+ to 100GbE QSFP28 to 200GbE QSFP56.  Highly parallel Ethernet interfaces more than 4 lanes wide like 400GbE have never reached high volume (more than 1M ports/year) and there is no reason to think this will change. 


According to Dell’Oro, more 100GbE switch ports shipped than 100GbE router ports last year for the first time.  This year, over 10X as many 100GbE switch ports are expected to ship than 100GbE router ports.  Routers ship low volumes of high speed ports initially, but switches overwhelm routers in port shipments when the technology is ready and the cost is low enough for switching.  This pattern of switching dominance is set to repeat again at 400GbE.  400GbE will ship for routers while 200GbE can come out of the gates in high volume like 40GbE.


Here’s a quick comparison of the differences between 200GbE and 400GbE:





Fits in QSFP Family of Modules

Yes, like 40GbE and 200GbE

No, requires 8 or 16 lanes

Supports Low Cost Copper

Yes, twinax and backplane

No copper here

Uses existing MMF cabling

Yes, 8 or 12 fiber MPO

No, requires new 32-fiber cabling

Supports low cost SMF modules

Yes, CWDM4 and LR4 in QSFP28

No, 8 lanes with tight wavelength spacing in higher power module

Target Market

Low cost switching

Premium routers


In booth_50GE_NGOATH_01a_0316.pdf, the presentation claims: 200G MAC to MAC provides no value.  I heard similar arguments against 40GbE in 802.3ba and 40GbE took off in switching in 2011 while 100GbE stayed high cost in routers until a 4-lane solution became available.  200GbE will add value by being lower cost/bit.  No Ethernet interface has proven to be low cost when it is highly parallel (>4 lanes).  Ethernet interfaces can sell millions of ports per year when they reach 4 lanes wide or less.


In nicholl_50GE_NGOATH_01_0316.pdf, the presentation claims “both a Standards and product viewpoint, 200GbE and 400GbE are likely to come out at the same time”.  I agree that the standards could come out at roughly the same time, but the products will be mainly different in character than in time.  High cost 400GbE will only be available in routers while low cost 200GbE will be in switches.  Go to any systems vendor’s website and there will be completely separate product lines for switches and routers.  Switches are for high volume and low cost while routing has very different and challenging requirements that are suited for high bandwidth deployments. 


I’m glad the objectives for 200GbE are already accepted by the Study Group.  I hope enough of you agree to keep 200GbE objectives in the project and prevent last minute changes with little justification beyond FUD.  End users will flock to 200GbE when they see a lower cost/bit performance - just like they did for 40GbE.



Scott Kipp