FAISAL DADA
flexible optical transport modems utilising FlexE
Management Entity (SDN)
FlexE
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Transported in a single Wavelength
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OPTICAL NETWORK
Modulations & Symbol Rates provide flexibility
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Increased flexibility: End to end transport link set up.
wavelengths using more than one modem per transport box or using more than one transport box. An Implementation for the Flexible Transport System We created a setup to demonstrate a programmable flexible transport system using a Xilinx UltraScale™ FPGA and an Acacia 400G Coherent Module. The Xilinx FPGA is used to create a large data flow (upto 400Gbps in increments of 100Gbps). The data flow is generated using a packet generator. The packets from the packet generator are then mapped to a Flex MAC and the entire data stream is mapped into a pre- standard implementation of FlexE. The FlexE signal consisting of multiple bonded 100GE PMD lanes is mapped to a format that can be sent to the Acacia 400G Module. The Acacia module houses two 200G capable modems which wrap the signal in an appropriate frame, adds the FEC and sends the signal over two wavelengths. On the way back the data from the optical link is received using a coherent receiver in
the Acacia module, FEC errors are corrected and the data is sent back to the FPGA. In the FPGA the multiple 100GE PMDs are aligned as per FlexE requirements and the full data pipe (200G, 300G or 400G) is recovered and sent to a packet monitor to be checked for errors. The packet generator and monitor allow us to emulate large data pipes that would typically have been received from packet gear. We can demonstrate a fully programmable and flexible end to end transport system by adjusting the data rate being generated in the FPGA and programming the modem chip to various modulation formats. In the implementation we have shown the following rates based on the different modulation schemes. Future Work, Applications and Summary Future work would include adding an SDN controlled interface such that the system could be controlled remotely. Additional FPGA features could include security using L1 or L2 encryption or using Interlaken to connect to NPUs to map large data flows to FlexE in the packet gear.
Applications like Data Center Interconnect and Flexible Transponders in packet or OTN gear can benefit from such a flexible implementation. Work in various standard bodies is being done to accommodate data pipes larger than 100Gbps like 400GE or OTUCn in the future. Utilising FlexE to bond existing interfaces allows for such large data pipes to be carried over existing transport gear today and will continue to benefit by connecting flexible transport gear to variable rate interfaces in the future. Our goal was to demonstrate the viability of a fully flexible transport system which is programmable end to end and can carry large traffic pipes. Such programmable and flexible systems will allow the use of optical gear with various newer modulations and baud rates, to fully utilise the link budget and provide rate, power and distance tradeoffs. It will also allow the systems to be fully programmable in a network controlled by higher-level management interfaces that can provide bandwidth and services on demand. Article written in collaboration with Glen Miller from Acacia Corporation.
physical interfaces, but can create traffic rates and modify them, provides a significant breakthrough to create a fully flexible system. Connection Setup Considerations To achieve a fully flexible transport link the end to end setup must be done such that all the links are flexible. The figure above also shows a simple setup connecting two pieces of packet equipment like routers or switches over a transport link. In such a system, the transport link controlled by the transport gear could be set to the various rates from 50Gbps to 700Gbps, as much as may be available in the transport gear. The client link can then be setup to increase in increments of 25Gbps using FlexE. A higher level management entity (SDN or other) may then choose to setup the entire connection based on application need, power tradeoffs or link budgets. A more elaborate connection may be set up where the data from the packet gear may be sent over multiple
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