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800G & 1.6T Ethernet: Innovations and Challenges

Posted on Sep 11, 2023 by
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The deployment of 5G networks, AI applications and IoT technology has increased the demand for higher bandwidth and data rates. As a result, there is increased anticipation and interest in 800G Ethernet and 1.6T networking. In this article, the key challenges and innovations for 800G Ethernet and 1.6T networking will be illustrated thoroughly.

800G & 1.6T Ethernet: Innovations and Challenges

Ethernet Speed Over Time

Challenges of Upgrading to 800G Ethernet and 1.6T Networking:

How to Increase the Speed and Capacity of 800G Ethernet?

The current implementation of 800G ethernet utilizes 8 channels at 100Gbps per channel, doubling the PAM4 speed from 50Gbps (previous generation) to 100Gbps. The 800G transceiver with 200Gbps per channel is under development, which creates a significant 800G challenge for 800G Ethernet.

Switch Silicon SerDes

Faster network switching chips are crucial for improving channel speeds in 800G Ethernet. Network switching chips enable low-latency switching between elements within the data center. To support the increase in overall switch chip bandwidth, the speed, quantity, and power of SerDes have also been increasing. SerDes speed has increased from 10 Gbit/sec to 112 Gbit/sec, and the number of SerDes around the chip has increased from 64 channels to 512 channels in the 51.2 Tbps generation. SerDes power consumption has become a significant part of the total system power. The next-generation switching chips will double the bandwidth once again, as 102.4T switches will have 512 channels of 200 Gb/s SerDes. These silicon switches will support 800G and 1.6T on 224 Gb/s channels.

Pulse Amplitude Modulation

High-order modulation increases the number of bits per symbol or the number of bits per unit interval (UI) and provides a trade-off between channel bandwidth and signal amplitude. PAM4 modulation offers backward compatibility with previous generations of products and provides a better signal-to-noise ratio (SNR) compared to higher modulation schemes, allowing for reduced forward error correction (FEC) overhead that contributes to latency. However, achieving PAM4 requires a better analog front-end (AFE) due to analog bandwidth limitations and advanced equalization implemented through innovative DSP schemes.

Currently, the industry may retain the versatility of PAM4 in 800G Ethernet or 1.6T networks while exploring alternative methods for high-speed data integrity maintenance. However, future generations of the standard may employ higher modulation schemes such as PAM6 or PAM8.

800G & 1.6T Ethernet: Innovations and Challenges

PAM4 signals have smaller eye heights, requiring tighter design margins for noise and jitter

How to Reduce Bit Error Rate in 800G Ethernet Network?

In most high-speed data standards, the presence of fine-tuning equalizers in transmitters and receivers ensures that the signals transmitted through the channel can be interpreted at the other end, compensating for signal attenuation in the channel. However, as faster speeds push the physical limits further, more sophisticated methods are required. One such solution is forward error correction (FEC).

Forward error correction involves transmitting redundant data to assist the receiver in reconstructing the signal with damaged bits. FEC algorithms can recover data frames from random errors but encounter burst errors when an entire frame is lost. Each FEC architecture has trade-offs and advantages in terms of coding gain, overhead, latency, and power efficiency. In a 224 Gb/s system, more complex FEC algorithms are needed to minimize burst errors.

800G & 1.6T Ethernet: Innovations and Challenges

Different FEC Architectures have Varying Tradeoffs

FEC Schemes
Example Options
Coding Gainover KP FEC
Overhead
Latency
Power/Area
End-to-end
RS (576,514,31)
-1.5 dB more
6% more
Incremental increase
Incremental increase
Segmented
KP and FECo
FECo dominant
FECo dominant
Significant increase
Significant increase
Concatenated
KP+BCH/Hamming
~0.5-1.5 dB
3% -6% more
Incremental increase
Incremental increase
 

How to Enhance Power Efficiency in 800G Ethernet Networks?

The most challenging issue faced by 800g or 1.6T Ethernet data centers is power consumption. The power consumption of optical modules has been increasing with each generation. As optical module designs mature, they become more efficient, resulting in a decrease in power consumption per bit. However, due to the average of 50,000 optical modules in each data center, the overall power consumption of the modules is still a concern. Co-packaged optical devices can reduce the power consumption per module by integrating optoelectronic conversion within the package. However, cooling requirements remain a challenge in this approach.

In 800G Ethernet, a key innovation of co-packaged optical devices is to move the optical components close enough to the bare die of the Switch ASIC to eliminate the need for an additional DSP (as shown in the diagram below).

800G & 1.6T Ethernet: Innovations and Challenges

Pluggable and Co-packaged Optics

What's the Timeline for 800G Ethernet & 1.6T Networking?

800G Ethernet is on the horizon, building upon the foundation laid by IEEE and OIF for 400G. The first 51.2T switch chip was released in 2022, supporting 64 ports of 800 Gb/s, and validation started on the initial batch of 800G optical modules.

This year, standard organizations will release the first version of IEEE 802.3df and OIF 224 Gb/s standards, providing developers with a better understanding of how to build 800G and 1.6T systems using 112 Gb/s and 224 Gb/s channels. Over the next two years, it is expected that standard organizations will finalize the physical layer standards and proceed with actual development and validation shortly thereafter.

800G & 1.6T Ethernet: Innovations and Challenges

Timeline for Upgrading to 800G and 1.6T Speeds

FS 800G Ethernet Modules

In order to cater to the current development prospects of high-performance computing, FS provides a series of 800G Ethernet modules. Our 800G Ethernet modules are engineered and tested for reliability to meet the ever-changing needs of modern networks. The following is the 800G Ethernet module of FS:

FS P/N 
 Power Consumption  Connector  Distance
 QDD-SR8-800G  ≤13W  MTP/MPO-16  50m
 QDD-DR8-800G  ≤16.5W  MTP/MPO-16  500m
 QDD800-PLR8-B1  ≤18W  MTP/MPO-16  10km
 OSFP-SR8-800G  ≤14W  Dual MTP/MPO-12  50m
 OSFP-DR8-800G  ≤16.5W  Dual MTP/MPO-12  500m
 OSFP-2FR4-800G  ≤16.5W  Dual LC Duplex  2km
 OSFP800-PLR8-B1  ≤16.5W  MTP/MPO-16  10km
 OSFP800-PLR8-B2  ≤16.5W  Dual MTP/MPO-12  10km
 OSFP800-2LR4-A2  ≤18W  Dual LC Duplex  10km

Conclusion

Currently, 400G is being deployed on a large scale, and there is still a long way to go for the data rate of 800G Ethernet, while the optimal path for 1.6T remains uncertain. Within just a few years, higher capacities, faster speeds, and significant efficiency improvements will undoubtedly be required. To be prepared for the expansion of these new technologies, it is necessary to start designing and planning from today onwards. With advanced technology and superior performance, FS is your trusted partner for the next generation of networking solutions. Upgrade your network to 800G with FS today and stay ahead in the digital era.