Data Distancing – Mellanox Announces 100G ER QSFP28 Transceiver for 40 km

100G, Cables, Transceivers

Linking InfiniBand, Ethernet Data Centers and Campuses Together

One thing you “would have seen at OFC2020” from the Mellanox LinkX cables and transceivers team is our new 40km 100G ER/4WDM-40 transceiver announcement for “Extended Reaches!” The Mellanox LinkX cables and transceivers team continues to add to our full 25G/100G DAC, AOC and transceiver portfolio for 25G-based networks and now supports links from 1/2 -meter copper DACs, 5-to100m AOCs and optical transceivers: SR, LR, SR4, PSM4, CWDM4, LR4 and now ER up to 40 km.These haveenough reach to cover very dense campus networks and even metro reaches between data centers.


100G ER QSFP28 Transceiver Features:

  • Up to 40 km or 25-mile links
  • Based on 4 EML lasers and APD receiver
  • Electrical interface (CAUI-4) compliant with IEEE 802.3bm
  • Compliant with 100G 4WDM-40 MSA technical specification rev 1.0
  • Based on LAN-WDM multiplexed 1310nm wavelength specifications
  • Up to 4.5 Watts power dissipation
  • 2-fiber duplex LC optical connector with single-mode fibers
  • Supports Ethernet & InfiniBand protocols


Not only, can the 100G ER transceiver be used for metro data center-to-data center links across cities but also across campus networks with complex and lossy infrastructures with multiple patch panels and connectors. While the optical power is expressed in meters, it really is about the link budget needed.  For example, complex data center and campus network infrastructures with lots of optical connector losses may need a 10km power transceiver to only span 200 meters.

Data Center Campus Application                                                                                                                                       Metro Application

The 100G ER transceiver operates in the Mellanox MetroX-2 InfiniBand switch and the 100G Spectrum SN2000 and Spectrum-2 and SN3000 series Ethernet switches.  Other switches are also being tested.


For InfiniBand, in the MetroX®-2 series switches, the 100G ER extends Mellanox’s InfiniBand RDMA solutions to local, campus and metro applications, enabling connections between data centers deployed across multiple geographically distributed sites. RDMA or Remote Direct Memory Access enables transferring data directly from one memory to another without have to run every byte through the CPU which not only takes a lot of time and induces latency, but also chews up one of the most expensive resources in the system – the CPU. RSMA enables bypassing the CPU for the most part and transferring data from point to point using only switches and network adapters linked with cables and transceivers.


This approach enables users to easily and effectively migrate application jobs from one InfiniBand center to another or combine the compute power of multiple remote data centers together for higher overall performance and scalability.



Making Sense of More Optical Buzzwords

The Mellanox 100G ER transceiver is based on the 4WDM-40 MSA, not the IEEE standards body.  There is quite a lot of confusion about this relatively new category of optical transceivers. The three contenders for 40km reaches are ER4, ER4-lite and 4WDM-40 and they are not all the same.


What’s the difference between ER4, ER4-lite and 4WDM-40 Transceiver Standards?

Although they all do 40km reaches, there are quite a bit of difference between these.  Bottom line is the 4WDM-40 is designed especially for low-cost, small form-factor, low-power consumption data center applications and supports the KR4 FEC standard. The ER4 is primarily a telecom-oriented part.


ER4:  is a dual rate Ethernet and OTU telecom part with standards set by the IEEE.  It generally uses a semiconductor optical amplifier (SOA) with a low-cost optical PIN detector but due to the power requirement usually requires a very large form-factor like CFP2.  Some designs can pack it into a QSFP28 with performance restrictions.


ER4-lite: uses Avalanche Photo Diodes (APDs) instead of SOAs and PIN detectors and can be fit into QSFP28 form-factor and supports 100GbE however without FEC and generally, only used for 30 km reaches.


4WDM-40: Data centers needed a low-cost, low-power, small QSFP28 form-factor simple solution for 40 km reaches without all the telco overhead, power, cost and complexities.  The 4WDM-40 affectionately called the 100G ER for “Extended Reach” was designed specifically for data center applications with network switches instead of complex telco routers and other specialized complex transmission equipment.


The 4WDM-40 was standardized by an independent standards group called the 4WDM.MSA and is not related to the IEEE ER4 efforts.  The 100G ER supports Ethernet-only and not the telecom OTU rates, however, Mellanox adapted it to run the 100G EDR InfiniBand protocol and supporting RDMA.  It uses the same ER4 WDM wavelength grid (1294-1310nm 4.5nm spacing) and an APD detector but no SOA.  It is designed for lowest cost solutions in Ethernet switch data center applications, so supports the popular data center oriented, low-latency, low-power consumption KR4 FEC. Most ER4 and ER4-lite transceivers do not support KR4 FEC.


Most InfiniBand applications are inside of data centers as low latency is key to InfiniBand.  Mellanox added InfiniBand support at 100G EDR rates enabling synchronizing RDMA across data centers and campuses as far as 40 km apart!


Bottom Line:

  • Mellanox 100G ER can link data centers and campuses together in “end-to-end” Mellanox systems with “plug & play” data center-oriented simplicity – generally not found with telco-oriented solutions.


  • Mellanox 100G ER enables transmitting InfiniBand RDMA across 40 km spans.


  • Extensively tested to run in Mellanox switch systems for Ethernet and InfiniBand protocols and guarantees out-of-the-box, plug & play, highest performance and lower cost.


Mellanox LinkX® brand of 25G/100G, 200G, and now 400G cables and transceivers is designed to support any data center-oriented application from ½-meter DAC to now 40Km ER optical reaches.


Contact your Mellanox sales representative, See the LinkX cables and transceivers website and have a visit to the Mellanox Store.



About Brad Smith

Brad is the Director of Marketing at Mellanox, based in Silicon Valley for the LinkX cables and transceivers business focusing on hyperscale, Web 2.0, enterprise, storage and telco markets. Recently, Brad was Product Line Manager for Intel’s Silicon Photonics group for CWDM4/CLR4 and QSFP28 product lines and ran the 100G CLR4 Alliance. Director of Marketing & BusDev at OpSIS MPW Silicon Photonics foundry. President/COO of LuxSonar Semiconductors ( Cirrus Logic) and co-founder & Director of Product Marketing of NexGen, a X86-compatible CPU company sold to AMD - now the X86 product line. Brad also has ~15 years in technology market research as Vice president of the Computer Systems group at Dataquest/Gartner; VP/Chief Analyst at RHK and Light Counting networking research firms. Brad started his career at Digital Equipment near Boston with the VAX 11/780 and has served as CEO, president/COO and on the board-of-directors of three start-up companies. Brad has a BSEE degree from the University of Massachusetts; MBA from University of Phoenix and holds 2 optical patents

Comments are closed.