In our fast-paced digital age, the thirst for speed and capacity in data transmission is insatiable. As businesses and data centers sprint to keep up, 400G optical modules are emerging as the revolutionary heroes of modern network infrastructure. Yet, with a myriad of options available, choosing the perfect 400G module can feel like navigating a complex maze. Fear not—this guide will illuminate the essential factors to consider, such as packaging, transmission standards, technical requirements, and compatibility, empowering you to make savvy choices and future-proof your network.

Unveiling the 400G Optical Module

Imagine a device that can send data at a blistering 400 gigabits per second—that’s the prowess of a 400G optical module. These high-performance transceivers not only leave their 100G and 200G predecessors in the dust but are meticulously crafted to cater to the escalating demands of cloud computing, AI, and big data. These modules are the linchpins of today’s high-speed, high-bandwidth networks, seamlessly integrated into data centers, wide area networks (WANs), and telecommunications infrastructure.

Key Features of 400G Optical Modules

1. Unmatched Bandwidth: Capable of a staggering 400 Gbps, these modules are the lifeline for bandwidth-hungry applications, be it in cloud computing, AI, or data analytics.
2. Versatile Transmission Standards: With options like 400GBASE-SR4, 400GBASE-LR8 and 400GBASE-SR8, these modules cater to varied transmission distances and use cases, helping you tailor your network setup to perfection.
3. Compact Design & Energy Efficiency: Designed with cutting-edge integrated circuit design and advanced optical technologies, 400G modules offer high-density performance while slashing power consumption, translating to lower energy costs and space savings in bustling data centers.
4. Sophisticated Multi-Channel Technology: Utilizing techniques like PAM4 (four-level pulse amplitude modulation), these modules pack more data bits into a single signal channel, ramping up data throughput.
5. Broad Applicability: From internal data center links to high-speed Ethernet and metropolitan area networks (MANs), 400G modules excel across diverse networking scenarios, delivering ultra-low latency and high bandwidth for expansive network growth.

Advantages of 400G Optical Modules

• Supercharged Network Capacity: These modules dramatically enhance network capacity, facilitating higher data density and transmission rates.
• Cost-Efficiency: Compared to their 100G and 200G counterparts, 400G modules offer a reduced cost per bandwidth unit, making them a smart investment for large-scale deployments.
• Future-Ready: As the demand for bandwidth skyrockets with the rise of 5G, cloud computing, AI, and IoT, 400G optical modules ensure your network is primed for the future.

400G Optical Module Industry Standards：

Ensuring your 400G optical modules deliver peak performance and seamless compatibility is paramount. This is where industry standards come into play, crafted by leading organizations like IEEE, OIF, and MSA. These standards are the unsung heroes that guarantee interoperability and consistent performance across a plethora of vendors and applications.

IEEE: Setting the Ethernet Benchmark

The Institute of Electrical and Electronics Engineers (IEEE) takes the lead in defining Ethernet standards, ensuring your 400G optical modules meet rigorous performance criteria. Notable standards include:

• IEEE 802.3bs: Launched in 2017, this spec outlines the physical layer for 400G and 200G Ethernet, covering variants like 400GBASE-SR8 (short distance over multimode fiber), 400GBASE-DR4 (500 meters over single-mode fiber), 400GBASE-FR4 (2 kilometers over single-mode fiber), and 400GBASE-LR8 (10 kilometers over single-mode fiber).

OIF: Mastering Modulation and Interoperability

The Optical Internetworking Forum (OIF) is a key player in promoting optical communication interoperability. A standout contribution is their advancement of PAM4 (4-Level Pulse Amplitude Modulation) technology. By doubling the data rate per channel from 50G NRZ to 100G PAM4, OIF enhances the transmission prowess of 400G modules.

MSA: Defining Versatile Form Factors

Multi-Source Agreements (MSAs) are crucial for defining the physical and electrical characteristics of optical modules, ensuring adaptability and efficiency:

• QSFP-DD MSA: Dictates the specs for 400G Quad Small Form-Factor Pluggable Double Density modules, a staple in high-density data centers.
• OSFP MSA: Introduces a novel form factor for 400G and future 800G modules, accommodating greater power needs and heat dissipation.
• COBO MSA: Focuses on on-board optics, where modules are directly soldered onto circuit boards, ideal for high-density, high-power environments.

Next, let’s discuss the packaging types for 400G optical modules. Currently, the main packaging forms for 400G modules include CDFP, CFP8, QSFP-DD, and OSFP. Although CDFP and CFP8 were early packaging solutions for 400G, their larger size and higher power consumption have limited their market adoption. In contrast, QSFP-DD and OSFP have become more popular choices due to their more compact size, lower power consumption, and greater flexibility, making them especially suitable for modern data centers and high-performance network environments.

Now, let’s focus on the two mainstream packaging types in the market: QSFP-DD & OSFP. and also,the 400G QSFP112, which is less commonly used, but has been more widely discussed.

Packaging Types for 400G Module

QSFP-DD (Quad Small Form Factor Pluggable Double Density)

Features:

• Double Density Design: QSFP-DD is a double-density extension of the original QSFP (Quad Small Form Factor Pluggable) package, supporting 8 channels at 50G each, totaling a 400G transmission rate.
• Backward Compatibility: QSFP-DD is compatible with existing QSFP+, QSFP28, and other 100G and 200G optical modules. This allows equipment manufacturers to continue using existing 100G and 200G modules in 400G equipment.
• Power Consumption: QSFP-DD has relatively low power consumption, typically between 12-15 watts, making it suitable for high-density deployments.
• Compact Size: Similar in size to QSFP28, it has a compact form factor that is ideal for high-density data center environments.

Advantages:

• Compact design supports high-density deployment.
• High bandwidth and low-power design meet the dual demands of speed and energy efficiency in modern data centers.
• High compatibility, suitable for various network devices.

Application Scenarios:

• Suitable for data center switches, routers, servers, and other equipment.
• Ideal for scenarios requiring high port density and low power consumption.

OSFP (Octal Small Form Factor Pluggable)

Features:

• Larger Size: The OSFP package is slightly larger than QSFP-DD, though it still supports 8 channels at 50G to achieve a 400G transmission rate.
• No Direct Backward Compatibility: OSFP does not directly support QSFP28 or earlier packaging types (though it can achieve compatibility through a module adapter). However, it is designed to support future high-speed upgrades, such as an 800G transmission rate, making it more scalable.
• High Power Support: OSFP supports power consumption up to 15-20 watts, making it suitable for long-distance transmission or complex application scenarios.
• Thermal Management: The OSFP design enhances heat dissipation, suitable for higher power modules.

Advantages:

• Supports higher power consumption, suitable for large-scale and high-performance optical communication needs.
• Enhanced heat dissipation capability ensures stable operation in high-density environments.
• Capable of supporting future 800G or even higher-speed optical modules.

Application Scenarios:

• Suitable for devices requiring long-distance transmission or higher power consumption, such as Metropolitan Area Networks (MAN) and Wide Area Networks (WAN).
• Ideal for future applications needing higher transmission rates, such as 800G or higher upgrade scenarios.

400G QSFP112

The QSFP112 is a high-performance module and connector system built on the current QSFP design, tailored to support 112 Gbps per lane within a 4-lane QSFP setup, enabling seamless 400G connectivity. This design supports the 400G QSFP ecosystem, allowing users of traditional QSFP interfaces to efficiently upgrade to 400G per port. By building on existing QSFP architecture, QSFP112 offers a cost-effective and time-efficient solution for enhancing link bandwidth, making the transition to 400G simpler and more affordable for established networks.

Features:

• Conforms to the QSFP-DD (Quad Small Form Factor Pluggable Double Density) standard 
• Compact design allows for high port density in network equipment racks 
• Backward compatible with previous QSFP form factors, including QSFP28 and QSFP56 
• Compatible with various network protocols such as Ethernet, Fibre Channel, and InfiniBand 
• Supports data transfer rates of up to 400Gbps using PAM4 (Pulse Amplitude Modulation with 4 levels) technology
• The QSFP112 transceiver typically consumes 3.5W less power than other 400G transceivers, a dramatic 29% reduction in power consumption making the QSFP112 the market leader in high speed transceivers.
• Average power consumption is about 10 watts or between 10-15 watts per module 
• Designed with energy efficiency in mind, consuming less power than previous models 

Application Scenarios:

• Primarily used in data centers to upgrade existing network infrastructure from 200G to 400G 
• Suitable for high-performance computing (HPC) environments requiring high-speed data transfer and low latency 
• Used in telecommunications networks to support high-speed data transmission over long distances 
• Ideal for future-proofing network infrastructure 

How Should I choose Between These Two Packaging Types?

Each packaging type has its own advantages. The choice should be made based on specific application requirements, such as power consumption, bandwidth needs, upgrade path, and physical space constraints.

• Backward Compatibility: If you need to continue using existing 100G or 200G optical modules, QSFP-DD is the optimal choice. It is best suited for environments where backward compatibility and high port density are essential. Its smaller size allows for more ports in a given space, making it ideal for data centers with space constraints
• Future Scalability: OSFP is the most future-proof option, supporting higher data rates and power consumption. It’s ideal for applications that require robust thermal management and have the potential for future expansion to 800Gb/s speeds.
• 400G QSFP112 : It offers a balance of high performance, energy efficiency, and compatibility. It’s ideal for data centers, HPC environments, and telecommunications networks looking to upgrade their infrastructure while maintaining compatibility with existing systems.

In our next article, we’ll dive deep into the key 400G transmission standards—VR4,SR4,SR4.2SR8, DR4, FR4, LR4, LR8, ER4 and ZR4. These standards vary by transmission distance, fiber type, and encoding methods, each tailored to unique application needs. We’ll break down the features and differences of each standard and offer practical guidance to help you confidently choose the right module. Don’t let the choices overwhelm you—stay tuned for clarity on 400G modules!https://cloudswit.ch/blogs/choose-400g-optical-modules-for-data-center/

Q&A about 400G Modules:

Q1: Does Asterfusion offer 400G switches?
A1: Absolutely! Asterfusion offers a cutting-edge 400G switch, specifically our self-developed 12.8T switch, which is powered by our enterprise version of SONiC NOS—AsterNOS. This switch is engineered to meet the demanding requirements of various applications, including AI, machine learning, data centers, high-performance computing (HPC), and distributed storage. Curious to learn more? Check out Asterfusion’s product page for all the details!

Q2: Can an OSFP optical module be used on one end of a 400G link while a QSFP-DD module is on the other end?
A2: Yes, it can. OSFP and QSFPDD are just different physical appearances of modules. As long as the module types are the same (for example, both are 400G-SR4 or both are 400G-DR4), OSFP and QSFPDD modules can be interoperable.

Q3: Can a QSFPDD module be used in an OSFP port?
A3: No! OSFP and QSFPDD are two completely different packaging forms, so a QSFPDD optical module cannot be used in an OSFP port. Likewise, an OSFP optical module cannot be used in a QSFPDD port.

Q4: What interface types are available for 400G modules?

• Duplex LC Interface: Similar to 100G-CWDM4, 40G-LR4, etc., modules like LR4, ER4, ER8, etc., use a duplex LC interface.
• MPO12 Interface (APC): Similar to 100G-SR4, 100G-PSM4, etc., modules like 400G-DR4, XDR4, PLR4, etc., use an MPO12 interface.
• MPO16 Interface (APC): For 400G-FR4/400G-SR8, using eight fibers for transmission and eight fibers for reception, with a total of 16 fibers completing the 400G transmission.

Q5: Can a 100G QSFP28 optical module be inserted into an OSFP port?

A5: Unfortunately, no. A 100G QSFP28 module cannot be directly plugged into an OSFP port. However, if you really need to bridge that gap, a converter module can be used to adapt it—just keep in mind that the link will still operate at 100G speeds.