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Special Interest Group on Next Generation Network meeting: Beyond 100G

Words: Mian Usman, Senior Network Architect, GÉANT

On December 13 2021, the Special Interest Group on Next Generation Network (SIG-NGN) held the first of a series of virtual meetings, getting together for the first time since the pandemic began. The last meeting was held in January 2019 at CERN in Geneva, Switzerland.

The meeting focused on the theme of “Beyond 100G” and included enlightening presentations from on the deployment and testing of transmission technologies faster than 100G.

Patrick Von Marten from Smart Optics gave an insightful overview of the “Transceivers beyond 100G”. He started with a picture of a transceivers from the 1980s which was almost the size of an iPad. He then gave a short overview of 100G optics, as the 400G grey optics are also based on the same standards.

400G standards and MSA’s for Grey Optics
400G standards and MSA’s for Grey Optics

His presentation raised an important question “Can we stay with the QSFP-28 form factor for transceivers beyond 100G?”. The answer according to the presenter is No. We need to have a big form factor and QSFP-DD is used for 400G which provides more space for electronics as it is longer than QSFP28. It is, however, backwards compatible so one could use QSFP-28 to run 100G on the same interface and when they are ready to move to 400G they can use QSFP-DD to upgrade to 400G. Patrick also provided a brief overview of Coherent 400G optics and Common Management Interface Specification (CMIS), and challenges with 800G optics.

The second presenter was Chris Tracy from the Energy and Science Network (ESnet) in the USA. The ESnet network provides connectivity to all the department of energy labs, experience sites and other user facilities. Chris provided information about three backbone links that they have upgraded to 400GE. The first link – which already running 400G wavelengths on that span but using only the 100GE client interfaces – was officially migrated from 100GE to 400GE in October 2021. The upgrade path was simpler as it did not require any change on the line side but only to move the client-side connections to the interface with QSFP-DD optics.  ESnet is also deploying a second transponder vendor and plans to upgrade most of the remaining 100G backbone links to 400GE.

Next, Guy Roberts -Senior network architect at GÉANT- provided a high-level overview of GÉANTs experience of 800G transmission field trial. His presentation focused on running 800G on the line side using the latest generation of Infinera data centre interconnect (DCI) boxes powered by the Infinera Capacity Engine 6 (ICE6).

GÉANT fibre between Amsterdam and Frankfurt
GÉANT fibre between Amsterdam and Frankfurt

The field trial was carried out on the GÉANT fibre between Amsterdam and Frankfurt in August 2021. The full news story about the field is outlined here.

Rob Smets from SURF shared their experiences with transport beyond 100G. Although it does not seem to be an immediate need for 400G in SURF’s national core network, they are running a 2 x 200G QPSK wave for one 400GE client connection on their cross-border fibre between Amsterdam and Geneva. They are currently 1dB OSNR short for running a 400G in a single wavelength and they plan to improve spectrum efficiency so they can operate up to 16 x 400GE services in 100GHz spectrum on a fibre between Amsterdam and Geneva. Learning from his experience, the presenter shared his advice to keep duplex fibre and where possible avoid MPO type client optics.

The final presentation was by Michal Hazlinsky from CESnet. They have recently modernised their network and deployed Flexgrid. The main ring in their network is 200G ready however they are running 100G in production and trialling 400G. They ran a trial of 400G on a 300KM link between Prague and Brno.

The next SIG-NGN virtual meeting on the topic of Non-IP Services will be held on the 15th February 2022. To register to attend the event, visit:

All presentations and the recording of the December 13 meeting can be found on:

SIG-NGN is part of the GÉANT Community Programme. More information on the Special Interest Group and other SIGs and TFs can be found at

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