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Connecting the DOTS with FlexEthernet

Thursday, June 14, 2018 | by Rudy Montgelas

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Connecting the DOTs with FlexEthernet


Ethernet Technology

For as long as I have been involved in communications, Ethernet has been one of the most important and widely used transmission schemes for both fiber and copper networking. Ethernet’s carrier sense multiple access/collision detection (CSMA/CD) method allows the handling of data transmission by multiple “stations” over a high bandwidth network.  Each station, wanting to transmit bits of information, uses a technique called collision detection to determine whether another station is trying to transmit data at the same time.  If a collision is detected, the station waits a random amount of time before transmitting the next bit of information, and then checks for another collision. Some of us will remember the days of the 10BASE-5 coaxial cable “vampire” Ethernet tap. 1 This was an early use of Ethernet over coax, or EoC.
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There’s a lot of other protocols and applications these days, either being transmitted over Ethernet, and under consideration for it.  Applications such as Fiber Channel over Ethernet, or FCoE, have been around for a while. Newly proposed Software Defined Video over Ethernet, or SDVoE are now in the works.  There’s also a new 2018 Ethernet roadmap that was just recently released.2
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Let’s face it, Ethernet has been around for a long time, and it continues to be the proven backbone for networking.
FlexEthernet (FlexE) for the “Need for Speed”

Transmission speeds in data centers are headed toward 400Gbps and beyond into the terabit per second region.  For 400Gbps, technologies such as Wavelength Division Multiplexing (WDM) and PAM4 encoding are being used with multifiber 12-F MPO connections to support 100GBPS using 4-fiber transmit and 4-fiber receive “lanes” or BAS-8 connectivity.3,4 To achieve even higher speeds, coherent optical techniques, are being employed for future fiber optic transceivers, as well as link aggregation and channelization, which is being proposed for a new version of Ethernet, called Flexible Ethernet, or FlexE.5
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FlexE has been proposed to the Ethernet standards group, by the Optical Interconnect Forum (OIF).  Through what’s called a FlexE Shim, it would flexibly allow Ethernet-based links to be aggregated into a single higher speed link, or lower speed links to be “channelized” from a single higher speed link, based on network demands between the connecting switches and servers. This channel allocation can be preprogrammed into the device’s chipsets or controlled remotely through software, once a common language is chosen for the FlexE architecture.  Consequently, there is currently significant interest in the development of the FlexE standard from many of the large networking device manufacturing companies.6

What’s it All Mean for DC’s Future

FlexE is going to be an important Ethernet standard that will drive the development of new software and hardware based solutions for more flexible and high-bandwidth fiber channel allocation in the network. And, it removes the interdependence of the network protocols on the specific transmission equipment being used.

Right now, there are only a handful of large companies providing high-speed Ethernet services who are driving FlexE development. But wth FlexE, we will all be seeing future Ethernet speeds heading up into the terabit region in the data center, along with the reduced latencies associated with less “hops” in the network for the future.Future routers and switches will have the FlexE capability baked-right-into into the hardware’s chip sets.  And, as software defined networking evolves, remote bandwidth channel allocation will be possible throughout the network by software. 

See you next time with another CTD.

References and Further Reading:
1 “Early Bus Networks (10BASE-5 and 10BASE-2)” June 1, 2018,
2 “New 2018 Ethernet Roadmap Looks to Future Speeds of 1.6 Terabits/s”,
3Legrand’s Connecting the Dots: “Base 8 Connectivity”, by Randy Harris, November 15, 2017
4 Legrand’s Connecting the Dots: “Boosting Fiber Optic Links”, by Rudy Montgelas, April 27, 2016
5 “Construction Zones on The Ethernet Roadmap”, March 24th, 2016 by Timothy Prickett Morgan,
6 “What is FlexEthernet and why is it so important”, by Helen Xenos, Ciena, May 24, 2017,
7 “FlexE - Wikipedia”, November 20, 2017,