800G Ethernet Innovations and Challenges

Ethernet is becoming increasingly important as we enter a data-driven world. Basically, Ethernet is a technology that connects computers and is designed to form a local network through which devices can communicate with other devices. However, over time, Ethernet has developed into a global data communication system, and its speed has developed from the initial 10Mbit/s to the current 800G or even 1.6T. This tremendous progress is not without challenges, but each breakthrough represents a huge leap in technology.

 

This article will explore the innovations and challenges of 800G Ethernet.

• 800G Ethernet
• The Current State of 800G Ethernet
  • Challenge 1: Switching Silicon SerDes
  • Challenge 2: Pulse Amplitude Modulation
• How to reduce the bit error rate of 800G Ethernet?
  • Forward Error Correction (FEC) Algorithm
  • Importance of FEC
  • Trade-offs and advantages of FEC
• How to improve the energy efficiency of 800G Ethernet?
  • Energy efficiency challenges
  • Co-packaged optics
  • Advantages of co-packaging technology
  • Improved energy efficiency
  • Package size reduction
  • Improved thermal management
  • Cooling Challenge
• Sum up

1. 800G Ethernet

800G Ethernet is a high-speed Ethernet technology used for data transmission and communication networks, providing a data transfer rate of 800 gigabits per second (800Gbps). It offers twice the speed of the previous generation 400G Ethernet, delivering greater bandwidth to meet the demands of handling large-scale data transfers, high-definition video, cloud computing, and the Internet of Things (IoT).

 

800G Ethernet employs advanced modulation techniques, typically using PAM4 (Pulse Amplitude Modulation-4), to transmit data, allowing each symbol to carry multiple bits of information and thereby increasing the data transfer rate.

 

800G Ethernet finds significant applications in data center networks, enhancing interconnectivity speeds between servers within the data center and facilitating large-scale data processing and cloud computing.

 

Implementing 800G Ethernet typically requires advanced network hardware and optical modules capable of supporting high-speed data transmission. These modules often employ low-power designs to improve energy efficiency.

 

The standardization of 800G Ethernet is overseen by the Institute of Electrical and Electronics Engineers (IEEE), ensuring interoperability among devices from different manufacturers.

 

2. The Current State of 800G Ethernet

The current implementation of 800G Ethernet utilizes eight channels, with each channel operating at a transmission rate of 100Gbps. This doubles the PAM4 (Pulse Amplitude Modulation-4) speed from the previous generation's 50Gbps to 100Gbps. The development of the next generation 800G transceivers aims to achieve a rate of 200Gbps per channel, which poses significant challenges as it requires simultaneously increasing the higher-order modulation and PAM4 data rates.

Challenge 1: Switching Silicon SerDes

Faster network switch chips are crucial for improving the channel speeds of 800G Ethernet. Network switch chips are used to achieve low-latency switching between various elements within a data center, which is vital for supporting high-performance computing and large-scale data transfers. To support the increased overall switch chip bandwidth, the speed, quantity, and power of SerDes (Serializer/Deserializer) have been continuously increasing. Currently, SerDes speeds have escalated from 10 Gbps to 112 Gbps, and the number of SerDes channels around the chip has risen from 64 to 51.2 Tbps, equivalent to 512 channels in one generation. However, SerDes power consumption has become a significant part of the overall system power consumption. The next generation of switch chips will once again double the bandwidth, as 102.4T switches will feature 512 200 Gbps SerDes channels. These silicon switches will support 800G and 1.6T on 224 Gbps channels.

 

Solutions:

 

• Higher-speed SerDes: Research and develop higher-speed SerDes technology to meet the growing demands of data transmission. This includes improving the speed of SerDes, reducing power consumption, and enhancing signal integrity.

 

• Power optimization:Adopt power-optimized design approaches to reduce the power consumption of SerDes. This involves utilizing advanced CMOS processes and low-power circuit designs.

Challenge 2: Pulse Amplitude Modulation

Higher-order modulation increases the number of bits per symbol or per unit interval (UI) and provides a trade-off between channel bandwidth and signal amplitude. Standards frequently explore higher-order modulation schemes to improve data rates. PAM4 modulation offers backward compatibility with previous generations of products and provides better signal-to-noise ratio (SNR) compared to higher modulation schemes, thereby reducing the overhead of forward error correction (FEC) that introduces latency. However, achieving PAM4 requires a better Analog Front End (AFE) due to analog bandwidth limitations and advanced equalization implemented through innovative digital signal processing (DSP) schemes.

 

Solutions:

 

• Improved Analog Front End (AFE):Research and develop higher-performance AFEs to support higher-order modulation schemes. This may involve more precise clock recovery, lower jitter, and better signal processing capabilities.

 

• Advanced Equalization Techniques: Adopt innovative DSP and equalization techniques to overcome distortions and noise in the channel. This helps improve the reliability of PAM4 signals.

 

• Explore Higher Modulation Schemes:While PAM4 has found wide application in the current 800G Ethernet, future standards may adopt higher-order modulation schemes like PAM6 or PAM8. This will increase the transmission rate per symbol but also introduce higher complexity. 

3. How to Reduce the bit error rate of 800G Ethernet?

In high-speed data transmission, signals are subject to various interferences and attenuations as they pass through channels. These include signal attenuation, noise, crosstalk, and other signal distortion factors. These factors can result in bit errors in the signal, known as errors. The presence of errors during data transmission can lead to significant data corruption, reducing data availability and integrity.

 

In previous high-speed data standards like 100G Ethernet, conventional equalizers and signal processing techniques were sufficient to mitigate the bit error rate. However, in the case of higher-speed 800G Ethernet, more sophisticated methods are required to address the challenges posed by higher bit error rates.

 

• Forward Error Correction (FEC) Algorithms

Forward Error Correction (FEC) is a widely used technique for reducing bit error rates. It involves adding redundant information during data transmission to help the receiver detect and correct errors in the transmission. FEC algorithms achieve this by adding redundant bits to the data frame, enabling the receiver to reconstruct lost or damaged data bits. This helps improve the reliability of data transmission, particularly in high-speed networks.

 

• Importance of FEC

FEC becomes particularly important in high-speed networks like 800G Ethernet. Due to higher data rates, bit error rates during transmission are typically higher. Therefore, more powerful FEC algorithms are needed to minimize the bit error rate and ensure the reliability of high-speed networks.

 

• Trade-offs and Advantages of FEC

Each FEC architecture involves trade-offs and advantages in terms of coding gain, overhead, delay, and power efficiency. Here are some common FEC architectures and their characteristics:

 

Reed-Solomon Coding

 

LDPC (Low-Density Parity-Check) Coding

 

BCH Coding

 

• Complex FEC Algorithms

In a 224 Gb/s system, more complex FEC algorithms are required to address higher bit error rate challenges. These algorithms may involve using more redundant data and more sophisticated error correction mechanisms to ensure the reliability of data transmission.

4. How to improve the efficiency of 800G Ethernet?

Each generation of optical modules has been experiencing an increase in power consumption, particularly in high-speed networks such as 800G and 1.6T Ethernet. While optical module designs have become more efficient, reducing power consumption per bit, the overall power consumption of modules remains a significant concern, especially in large-scale data centers.

 

• Energy Efficiency Challenge

Improving the energy efficiency of 800G Ethernet is an important challenge, particularly in large-scale data centers. The energy consumption of data centers has significant impacts on cost, environment, and sustainability. Therefore, reducing the power consumption of 800G Ethernet equipment is crucial.

 

• Co-packaged Optics Transceiver

One approach to address the power consumption challenge of optical modules is the adoption of co-packaged optics. This technology reduces the power consumption per module by integrating optic-electronic conversion functions within the module's packaging. Co-packaged optics offers several advantages, including improved energy efficiency and smaller packaging size.

• Advantages of Co-packaged Technology

 

1. Energy Efficiency Improvement

Co-packaged optics enhances energy efficiency by integrating optoelectronic conversion functions within the optical module. This integration reduces energy losses during optical signal conversion and transmission. As a result, the power consumption per bit decreases while providing higher energy efficiency.

 

2. Smaller Packaging Size

Co-packaged technology also reduces the packaging size of optical modules. This is particularly important for large-scale data centers that require more devices to be accommodated within limited space. Smaller packaging sizes improve data center scalability and layout flexibility.

 

3. Improved Thermal Management

With reduced power consumption, co-packaged optics generates relatively less heat. This helps improve thermal management in data centers, reducing cooling requirements and operational costs.

 

• Cooling Challenge

However, co-packaged optics also introduces new challenges, one of which is cooling. The heat generated by integrated optoelectronic converters within the packaging needs to be efficiently dissipated to prevent overheating and performance degradation. Therefore, designing efficient cooling solutions is crucial for the successful implementation of co-packaged technology.

 

5. Sum Up

The existing Ethernet technology is currently deploying 400G on a large scale, and there is still a long way to go before reaching the data rate of 800G. However, Ethernet transmission technology is continuously evolving and innovating. 800G multimode optical modules/AOCs/DACs are expected to continue leading the development in the networking field, providing strong support for the network requirements of the digital era. As a professional module manufacturer, NADDOD produces optical modules ranging from 1G to 400G. We welcome everyone to learn about and purchase our products.