Author Archives: Admin

Gigabit Ethernet Switch Selection Guide

In recent times, high-speed networks have become the pursuit for businesses and households across the globe, making daily life more comfortable and facilitating business growth. Gigabit switches play an important role in building high-speed networks and are widely used around the world. This article introduces the different types of 1G network switches, and how to choose the right Gigabit Ethernet switch, as well as FS switch recommendations.

What is a Gigabit Switch?

A gigabit switch is a type of Ethernet network switch that allows devices to be connected to a LAN at speeds of 1 Gbps or higher. Gigabit Ethernet replaced Fast Ethernet as a new network standard for increased speed. A Gigabit Ethernet switch is a higher version of a Fast Ethernet switch, meeting the demands of internet service providers for high speeds. 1G Ethernet switches are available in a variety of configurations, forming various types of switches to provide different services:

Unmanaged switches are designed to be plug-and-play with fixed configuration, providing basic connectivity for a small LAN or single user. These switches are normally used in small businesses where precise network control is not as crucial.

Managed switches are designed with greater control and advanced functionality to support the user experience, security, manageability, and scalability. They allow Ethernet devices to connect with each other, realizing the ability to configure, manage, and monitor local area network (LAN) traffic.

Smart switches feature limited management functions, allowing traffic self-management. They offer less scalability than other switches and can be used as infrastructure for smaller and less complex networks.

PoE switches support data transmission and power supply for several network devices using an existing Ethernet cable. They greatly simplify cabling and increase the flexibility and reach of connected systems.

FS Gigabit Switches: Suitable for Various Networking Requirements

With extensive industry experience and expertise, FS offers an exclusive line of 1G network switches with a wide range of port types and rich functional features, suitable for a variety of different applications. These switches offer versatile designs for better operational performance, helping to ensure a more secure experience and build a sustainable network for the future.

ModelsPortsPoE SupportedManaged UnmanagedFeatures Supported
S3900-48T6S-R48x 10/100/1000BASE-T RJ45 | 6x 10G SFP+non-PoEManagedQoS, IGMP Snooping, Link Aggregation, IPv6, L3 Static Routing RIP, OSPF
S3900-24T4S-R24x 10/100/1000BASE-T RJ45 | 4x 10G SFP+non-PoEManaged
S5810-28FS28x 1G SFP, 8x 1G RJ45/SFP Combo | 4x 1G/10G SFP+non-PoEManaged
S5810-48FS48x 1G SFP | 4x 1G/10G SFP+non-PoEManaged
S3150-8T2FP8x 10/100/1000BASE-T RJ45 | 2x 1G SFPPoE+Managed
S3400-24T4FP24x 10/100/1000BASE-T RJ45 | 4x 1G RJ45/SFP ComboPoE+Managed
S3260-16T4FP16x 10/100/1000BASE-T RJ45 | 2x 1G SFP, 2x 1G RJ45/SFP ComboPoE+Managed
IES3100-8TF-P8x 10/100/1000BASE-T RJ45 | 2x 100/1000/2500BASE-X SFPPoE+ManagedVLAN, QoS, LACP, IGMP, ACL, DHCP, Static Routing, MSTP

How to Select the Right Gigabit Switch for Your Network?

Ethernet switches play a significant role in enterprise network architecture and deserve serious selection. The following are the factors to consider when selecting 1G switches, which can provide you with some guidance.

Number of Ports You Need

First of all, determine how many network switch ports you need for your network. You need to not only calculate the number of connected devices in your home or business environment but also anticipate future connectivity needs. If it’s just for a home network that needs to connect three devices and a router, an 8 or 12-port Gigabit Ethernet switch is appropriate, due to the capability of future-proofing and connectivity for other devices provided. If you need a switch for a large network in a fast-growing enterprise, 24-port and 48-port managed switches are good choices, such as FS S3900-24T4S-R and FS S3900-48T6S-R.

Capability to Power Devices

Power over Ethernet (PoE) has become an important factor for users to consider when purchasing a network switch in recent years. This technology enables the capability to use existing Ethernet cables to power connected devices, such as VoIP phones, network surveillance cameras, or wireless access points. If you need this function, select a PoE Gigabit Ethernet switch. Make sure the power per port (in watts) and the total power budget of the PoE ports meet the needs of your network devices.Check FS S3400-24T4FP to see if it meets your needs.

Features

The features of network switches determine the functions and services they can offer. Unmanaged switches and smart switches lack network management and monitoring capabilities. Managed switches provide features, such as traffic management, troubleshooting, access controls, and monitoring. Some common features, including LACP, VLAN, QoS, IGMP Snooping, Link Aggregation, and OSPF, also need to be considered. FS 1G network switches are designed as managed switches with a rich set of features that encompass the above features.Other features, such as noise, may be overlooked. However, for homes or small offices, it is important to consider the noise generated by 1G network switches. FS S3150-8T2FP switch has a low-power and noiseless design, and supports secure desktop connectivity, suitable for deployments in working areas or home scenarios. In conclusion, before choosing a switch, double-check that it provides the features you need.

Applications

Special application scenarios will place additional requirements on Gigabit switches. For example, industrial scenarios pose higher requirements on the switch in terms of operating temperature, enclosure design, management, and durability. You need to check whether the Gigabit Ethernet switch can keep working well in the application scenario you want.If you need a switch for industrial scenarios, the FS IES3100-8TF-P can meet your needs to maintain stable operation in harsh environments, such as low temperatures and high vibration, and to enable easy network management.

The Closing Thought

To build a future-proof and reliable network, the selection of a switch needs to be done carefully, considering multiple aspects. I hope the above points will be helpful to you. Besides, FS offers a wide range of Gigabit network switches, one of which may meet your needs. check FS.com to know more.

How 400G Ethernet Influences Enterprise Networks?

Since the approval of its relevant 802.3bs standard from the IEEE in 2017, 400GbE Ethernet has become the talk of the town. The main reason behind it is the ability of this technology to beat the existing solutions by a mile. With its implementation, the current data transfer speeds will simply see a fourfold increase. Vigorous efforts are being made by the cloud service providers and network infrastructure vendors to pace up the deployment. However, there are a number of challenges that can hamper its effective implementation and hence, the adoption.

In this article, we will have a detailed look into the opportunities and the challenges linked to the successful implementation of 400G Ethernet enterprise network. This will provide a clear picture of the impact this technology will have on large-scale organizations.

Opportunities for 400G Ethernet Enterprise Networks

  • Better management of the traffic over video streaming services
  • Facilitates IoT device requirements
  • Improved data transmission density

How can 400G Ethernet assist enterprise networks in handling growing traffic demands?

Rise of 5G connectivity

Rising traffic and bandwidth demands are compelling the CSPs for rapid adoption of 5G both at the business as well as the customer end. A successful implementation requires a massive increase in bandwidth to cater for the 5G backhaul. In addition, 400G can provide CSPs with a greater density in small cells development. 5G deployment requires the cloud data centers to be brought closer to the users as well as the devices. This streamlines the edge computing (handling time-sensitive data) part, which is another game-changer in this area.5G

Data Centers Handling Video Streaming Services Traffic

The introduction of 400GbE Ethernet has brought a great opportunity for the data centers working behind the video streaming services as Content Delivery Networks. This is because the growing demand for bandwidth is going out of hand using the current technology. As the number of users increased, the introduction of better quality streams like HD and 4K has put additional pressure on the data consumption. Therefore, the successful implementation of 400GbE would come as a sigh of relief for the data centers. Apart from rapid data transferability, issues like jitter will also be brought down. Furthermore, large amounts of data transfer over a single wavelength will also bring down the maintenance cost.

High-Performance Computing (HPC)

The application of high-performance computing is in every industry sub-vertical whether it is healthcare, retail, oil & gas or weather forecasting. Real-time analysis of data is required in each of these fields and it is going to be a driver for the 400G growth. The combined power of HPC and 400G will bring out every bit of performance from the infrastructure leading to financial and operational efficiency.400G Ethernet

Addressing the Internet of Things (IoT) Traffic Demands

Another opportunity that resides in this solution is for the data centers to manage IoT needs. Data generated by the IoT devices is not large; it is the aggregation of the connections that actually hurts. Working together, these devices open new pathways over internet and Ethernet networks which leads to an exponential increase in the traffic. A fourfold increase in the data transfer speed will make it considerably convenient for the relevant data centers to gain the upper hand in this race.

Greater Density for Hyperscale Data Centers

In order to meet the increasing data needs, the number of data centers is also seeing a considerable increase. A look at the relevant stats reveals that 111 new Hyperscale data centers were set up during the last two years, and 52 out of them were initiated during peak COVID times when the logistical issues were also seeing an unprecedented increase. In view of this fact, every data center coming to the fore is looking to setup 400GbE. Provision of greater density in fiber, racks, and switches via 400GbE would help them incorporate huge and complex computing and networking requirements while minimizing the ESG footprint at the same time.

Easier Said Than Done: What Are the Challenges In 400G Ethernet technology

Below are some of the challenges enterprise data centers are facing in 400G implementation.

Cost and Power Consumption

Today’s ecosystem of 400G transceivers and DSP are power-intensive. Currently, some transceivers don’t support the latest MSA. They are developed uniquely by different vendors using their proprietary technology.

Overall, the aim is to reduce $/gigabit and watts/gigabit.

The Need for Real-World Networking Plugfests

Despite the standard being approved by IEEE, a number of modifications still need to be made in various areas like specifications, manufacturing, and design. Although the conducted tests have shown promising results, the interoperability needs to be tested in real-world networking environments. This would outline how this technology is actually going to perform in enterprise networks. In addition, any issues faced at any layer of the network will be highlighted.

Transceiver Reliability

Secondly, transceiver reliability also comes as a major challenge in this regard. Currently, the relevant manufacturers are finding it hard to meet the device power budget. The main reason behind that is the use of a relatively older design of QSFP transceiver form factor as it was originally designed for 40GbE. Problems in meeting the device power budget lead to issues like heating, optical distortions, and packet loss.

The Transition from NRZ to PAM-4

Furthermore, the shift from binary non-return to zero to pulse amplitude modulation with the introduction of 400GbE also poses a challenge for encoding and decoding. This is because NRZ was a familiar set of optical coding whereas PAM-4 requires involvement of extensive hardware and an enhanced level of sophistication. Mastering this form of coding would require time, even for a single manufacturer.from NRZ to PAM-4

Greater Risk of Link Flaps

Enterprise use of 400GbE also increases the risk of link flaps. Link flaps are defined as the phenomenon involving rapid disconnection in an optical connection. Whenever such a scenario occurs, auto-negotiation and link-training are performed before the data is allowed to flow again. While using 400GbE, link flaps can occur due to a number of additional reasons like problems with the switch, design problems with the -transceiver, or heat.

Inference

The true deployment of 400GbE Ethernet enterprise network is undoubtedly going to ease management for cloud service providers and networking vendors. However, it is still a bumpy road. With the modernization and rapid advancements in technology, scalability is going to become a lot easier for the data centers. Still, we are still a long way from the destination of a successful implementation. With higher data transfer rates easing traffic management, a lot of risks to the fiber alignment and packet loss still need to be tackled.

Article Source: How 400G Ethernet Influences Enterprise Networks?

Related Articles:

PAM4 in 400G Ethernet application and solutions

400G OTN Technologies: Single-Carrier, Dual-Carrier and Quad-Carrier

Coherent Optics and 400G Applications

In today’s high-tech and data-driven environment, network operators face an increasing demand to support the ever-rising data traffic while keeping capital and operation expenditures in check. Incremental advancements in bandwidth component technology, coherent detection, and optical networking have seen the rise of coherent interfaces that allows for efficient control, lower cost, power, and footprint.

Below, we have discussed more about 400G, coherent optics, and how the two are transforming data communication and network infrastructures in a way that’s beneficial for clients and network service providers.

What is 400G?

400G is the latest generation of cloud infrastructure, which represents a fourfold increase in the maximum data-transfer speed over the current maximum standard of 100G. Besides being faster, 400G has more fiber lanes, which allows for better throughput (the quantity of data handled at a go). Therefore, data centers are shifting to 400G infrastructure to bring new user experiences with innovative services such as augmented reality, virtual gaming, VR, etc.

Simply put, data centers are like an expressway interchange that receives and directs information to various destinations, and 400G is an advancement to the interchange that adds more lanes and a higher speed limit. This not only makes 400G the go-to cloud infrastructure but also the next big thing in optical networks.

400G

What is Coherent Optics?

Coherent optical transmission or coherent optics is a technique that uses a variation of the amplitude and phase or segment of light and transmission across two polarizations to transport significantly more information through a fiber optic cable. Coherent optics also provides faster bit rates, greater flexibility, modest photonic line systems, and advanced optical performance.

This technology forms the basis of the industry’s drive to embrace the network transfer speed of 100G and beyond while delivering terabits of data across one fiber pair. When appropriately implemented, coherent optics solve the capacity issues that network providers are experiencing. It also allows for increased scalability from 100 to 400G and beyond for every signal carrier. This delivers more data throughput at a relatively lower cost per bit.

Coherent

Fundamentals of Coherent Optics Communication

Before we look at the main properties of coherent optics communication, let’s first understand the brief development of this data transmission technique. Ideally, fiber-optic systems came to market in the mid-1970s, and enormous progress has been realized since then. Subsequent technologies that followed sought to solve some of the major communication problems witnessed at the time, such as dispersion issues and high optical fiber losses.

And though coherent optical communication using heterodyne detection was proposed in 1970, it did not become popular because the IMDD scheme dominated the optical fiber communication systems. Fast-forward to the early 2000s, and the fifth-generation optical systems entered the market with one major focus – to make the WDM system spectrally efficient. This saw further advances through 2005, bringing to light digital-coherent technology & space-division multiplexing.

Now that you know a bit about the development of coherent optical technology, here are some of the critical attributes of this data transmission technology.

  • High-grain soft-decision FEC (forward error correction):This enables data/signals to traverse longer distances without the need for several subsequent regenerator points. The results are more margin, less equipment, simpler photonic lines, and reduced costs.
  • Strong mitigation to dispersion: Coherent processors accounts for dispersion effects once the signals have been transmitted across the fiber. The advanced digital signal processors also help avoid the headaches of planning dispersion maps & budgeting for polarization mode dispersion (PMD).
  • Programmability: This means the technology can be adjusted to suit a wide range of networks and applications. It also implies that one card can support different baud rates or multiple modulation formats, allowing operators to choose from various line rates.

The Rise of High-Performance 400G Coherent Pluggables

With 400G applications, two streams of pluggable coherent optics are emerging. The first is a CFP2-based solution with 1000+km reach capability, while the second is a QSFP DD ZR solution for Ethernet and DCI applications. These two streams come with measurement and test challenges in meeting rigorous technical specifications and guaranteeing painless integration and placement in an open network ecosystem.

When testing these 400G coherent optical transceivers and their sub-components, there’s a need to use test equipment capable of producing clean signals and analyzing them. The test equipment’s measurement bandwidth should also be more than 40-GHz. For dual-polarization in-phase and quadrature (IQ) signals, the stimulus and analysis sides need varying pulse shapes and modulation schemes on the four synchronized channels. This is achieved using instruments that are based on high-speed DAC (digital to analog converters) and ADC (analog to digital converters). Increasing test efficiency requires modern tools that provide an inclusive set of procedures, including interfaces that can work with automated algorithms.

Coherent Optics Interfaces and 400G Architectures

Supporting transport optics in form factors similar to client optics is crucial for network operators because it allows for simpler and cost-effective architectures. The recent industry trends toward open line systems also mean these transport optics can be plugged directly into the router without requiring an external transmission system.

Some network operators are also adopting 400G architectures, and with standardized, interoperable coherent interfaces, more deployments and use cases are coming to light. Beyond DCI, several application standards, such as Open ROADM and OpenZR+, now offer network operators increased performance and functionality without sacrificing interoperability between modules.

Article Source:Coherent Optics and 400G Applications

Related Articles:
Typical Scenarios for 400G Network: A Detailed Look into the Application Scenarios
How 400G Ethernet Influences Enterprise Networks?
ROADM for 400G WDM Transmission

400G Multimode Fiber: 400G SR4.2 vs 400G SR8

Cloud and AI applications are driving demand for data rates beyond 100 Gb/s, moving to high-speed and low-power 400 Gb/s interconnects. The optical fiber industry is responding by developing two IEEE 400G Ethernet standards, namely 400GBASE-SR4.2 and 400GBASE-SR8, to support the short-reach application space inside the data center. This article will elaborate on the two standards and their comparison.

400GBASE-SR4.2

400GBASE-SR4.2, also called 400GBASE-BD4.2, is a 4-pair, 2-wavelength multimode solution that supports reaches of 70m (OM3), 100m (OM4), and 150m (OM5). It is not only the first instance of an IEEE 802.3 solution that employs both multiple pairs of fibers and multiple wavelengths, but also the first Ethernet standard to use two short wavelengths to double multimode fiber capacity from 50 Gb/s to 100 Gb/s per fiber.

400GBASE-SR4.2 operates over the same type of cabling used to support 40GBASE-SR4, 100GBASE-SR4 and 200GBASE-SR4. It uses bidirectional transmission on each fiber, with each wavelength traveling in opposite directions. As such, each active position at the transceiver is both a transmitter and a receiver, which means 400GBASE-SR4.2 has eight optical transmitters and eight optical receivers in a bidirectional optical configuration.

The optical lane arrangement is shown as follows. The leftmost four positions labeled TR transmit wavelength λ1 (850nm) and receive wavelength λ2 (910nm). Conversely, the rightmost four positions labeled RT receive wavelength λ1 and transmit wavelength λ2.

400GBASE-SR4.2 fiber interface

400GBASE-SR8

400GBASE-SR8 is an 8-pair, 1-wavelength multimode solution that supports reaches of 70m (OM3), 100m (OM4 & OM5). It is the first IEEE fiber interface to use eight pairs of fibers. Unlike 400GBASE-SR4.2, it operates over a single wavelength (850nm) with each pair supporting 50 Gb/s transmission. In addition, it has two variants of optical lane arrangement. One variant uses the 24-fiber MPO, configured as two rows of 12 fibers, and the other interface variant uses a single-row MPO-16.

400GBASE-SR8 fiber interface variant 1
400GBASE-SR8 fiber interface variant 2

400GBASE-SR8 offers flexibility of fiber shuffling with 50G/100G/200G configurations. It also supports breakout at different speeds for various applications such as compute, storage, flash, GPU, and TPU. 400G-SR8 QSFP DD/OSFP transceivers can be used as 400GBASE-SR8, 2x200GBASE-SR4, 4x100GBASE-SR2, 8x50GBASE-SR.

400G SR4.2 vs. 400G SR8

As multimode solutions for 400G Ethernet, 400GBASE-SR4.2 and 400GBASE-SR8 share some features, but they also differ in a number of ways as discussed in the previous section.

The following table shows a clear picture of how they compare to each other.

 400GBASE-SR4.2400GBASE-SR8
AllianceIEEE 802.3cmIEEE 802.3cm (breakout: 802.3cd)
Max reach150m over OM5100m over OM4/OM5
Fibers8 fibers16 fibers (ribbon patch cord)
Wavelength2 wavelengths (850nm and 910nm)1 wavelength (850nm)
BiDi technologySupport/
Signal modulation formatPAM4 signalingPAM4 signaling
LaserVCSELVCSEL
Form factorQSFP-DD, OSFPQSFP-DD, OSFP

400GBASE-SR8 is technically simple but requires a ribbon patch cord with 16 fibers. It is usually built with 8 VCSEL lasers and doesn’t include any gearbox, so the overall cost of modules and fibers remains low. By contrast, 400GBASE-SR4.2 is technically more complex so the overall cost of related fibers or modules is higher, but it can support a longer reach.

In addition, 400GBASE-SR8 offers both flexibility and higher density. It supports fiber shuffling with 50G/100G/200G configurations and fanout at different I/O speeds for various applications. A 400G-SR8 QSFP-DD transceiver can be used as 400GBASE-SR8, 2x200GBASE-SR4, 4x100GBASE-SR2, or 8x50GBASE-SR.

400G SR4.2 & 400G SR8: Boosting Higher Speed Ethernet

As multimode fiber continues to evolve to serve growing demands for speed and capacity, both 400GBASE-SR4.2 and 400GBASE-SR8 help boost 400G Ethernet and scale up multimode fiber links too ensure the viability of optical solutions for various demanding applications.

The two IEEE 802.3cm standards provide a smooth evolution path for Ethernet, boosting cloud-based services and applications. Future advances point toward the ability to support even higher data rates as they are upgraded to the next level. The data center Industry will take advantage of the latest multimode fiber technology such as OM5 fiber, and use multiple wavelengths to transmit 100 Gb/s and 400 Gb/s over fibers over short reach of more than150 meters.

Beyond 2021-2022 timeframe, once an 800 Gb/s Ethernet standard is standardized, using more advanced technology with two-wavelength operation could create an 800 Gb/s, four-pair link. At the same time a single wavelength could support an 800 Gb/s eight-pair link. In this sense, 400GBASE-SR4.2 and 400GBASE-SR8 are setting the pace for a promising future.

Article Source: 400G Multimode Fiber: 400G SR4.2 vs 400G SR8

Related Articles:

400G Modules: Comparing 400GBASE-LR8 and 400GBASE-LR4
400G Optics in Hyperscale Data Centers
How 400G Has Transformed Data Centers

Importance of FEC for 400G

The rapid adoption of 400G technologies has seen a spike in bandwidth demands and a low tolerance for errors and latency in data transmission. Data centers are now rethinking the design of data communication systems to expand the available bandwidth while improving transmission quality.

Meeting this goal can be quite challenging, considering that improving one aspect of data transmission consequently hurts another. However, one solution seems to stand out from the rest as far as enabling reliable, efficient, and high-quality data transmission is concerned. We’ve discussed more on Forward Error Correction (FEC) and 400G technology in the sections below, including the FEC considerations for 400Gbps Ethernet.

What Is FEC?

Forward Error Correction is an error rectification method used in digital signals to improve data reliability. The technique is used to detect and correct errors in data being transmitted without retransmitting the data.

FEC introduces redundant data and the error-correcting code before data transmission is done. The redundant bits/data are complex functions of the original information and are sent multiple times since an error can appear in any transmitted samples. The receiver then corrects errors without requesting retransmission of the data by acknowledging only parts of the data with no apparent errors.

FEC codes can also generate bit-error-rate signals used as feedback to fine-tune analog receiving electronics. The FEC code design determines the number of missing bits that can be corrected. Block codes and convolutional codes are the two FEC code categories that are widely used. Convolutional codes handle arbitrary-length data and use the Viterbi algorithm for decoding purposes. On the other hand, block codes handle fixed-size data packets, and partial code blocks are decoded in polynomial time to the code block length.

FEC

What Is 400G?

This is the next generation of cloud infrastructure widely used by high-traffic volume data centers, telecommunication service providers, and other large enterprises with relentless data transmission needs. The rapidly increasing network traffic has seen network carriers continually face bandwidth challenges. This exponential sprout in traffic is driven by the increased deployments of machine learning, cloud computing, artificial intelligence (AI), and IoT devices.

Compared to the previous 100G solution, 400G, also known as 400GbE or 400GB/s, is four times faster. This Terabit Ethernet transmits data at 400 billion bits per second, i.e., in optical wavelength; hence it’s finding application in high-speed, high-performance deployments.

The 400G technology also delivers the power, data density, and efficiency required for cutting-edge technologies such as virtual reality (VR), augmented reality (AR), 5G, and 4K video streaming. Besides consuming less power, the speeds also support scale-out and scale-up architectures by providing high density, low-cost-per-bit, and reliable throughput.

Why 400G Requires FEC

Several data centers are adopting 400 Gigabit Ethernet, thanks to the faster network speeds and expanded use cases that allow for new business opportunities. This 400GE data transmission standard uses the PAM4 technology, which offers twice the transmission speed of NRZ technology used for 100GE.

The increased speed and convenience of PAM4 also come with its own challenges. For instance, the PAM4 transmission speed is twice as fast as that of NRZ, but the signal levels are half that of 100G technology. This degrades the signal-to-noise ratio (SNR); hence 400G transmissions are more susceptible to distortion.

Therefore, forward error correction (FEC) is used to solve the waveform distortion challenge common with 400GE transmission. That said, the actual transmission rate of a 400G Ethernet link is 425Gbps, with the additional 25 bits used in establishing the FEC techniques. 400GE elements, such as DR4 and FR4 optics, have transmission errors, which FEC helps rectify.

FEC Considerations for 400Gbps Ethernet

With the 802.3bj standards, FEC-related latency is often targeted to be equal to or less than 100ns. Here, the receive time for FEC-frame takes approximately 50ns, with the rest time budget used for decoding. This FEC latency target is practical and achievable.

Using similar/same FEC code for the 400GbE transmission makes it possible to achieve lower latency. But when a higher coding gain FEC is required, e.g., at the PMD level, one can trade off FEC latency for the desired coding gain. It’s therefore recommended to keep a similar latency target (preferably 100ns) while pushing for a higher coding gain of FEC.

Given that PAM4 modulation is used, FEC’s target coding gain (CG) could be over 8dB. And since soft-decision FEC comes with excessive power consumption, it’s not often preferred for 400GE deployments. Similarly, conventional block codes with their limited latency need a higher overclocking ratio to achieve the target.

Assuming that a transcoding scheme similar to that used in 802.3bj is included, the overclocking ratio should be less than 10%. This helps minimize the line rate increase while ensuring sufficient coding gain with limited latency.

So under 100ns latency and less than 10% overclocking ratio, FEC codes with about 8.5dB coding gain are realizable for 400GE transmission. Similarly, you can employ M (i.e., M>1) independent encoders for M-interleaved block codes instead of using parallel encoders to achieve 400G throughput.

Conclusion

400GE transmission offers several benefits to data centers and large enterprises that rely on high-speed data transmission for efficient operation. And while this 400G technology is highly reliable, it introduces some transmission errors that can be solved effectively using forward error correction techniques. There are also some FEC considerations for 400G Ethernet, most of which rely on your unique data transmission and network needs.

Article Source: Importance of FEC for 400G

Related Articles:
How 400G Ethernet Influences Enterprise Networks?
How Is 5G Pushing the 400G Network Transformation?
400G Transceiver, DAC, or AOC: How to Choose?