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Comparison of 100G QSFP28 Multimode Transceivers: 100G SRBD VS 100G SWDM4

Updated on Oct 8, 2024 by
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In the era of cloud computing and 5G networks, the demand for high-speed data transmission is reshaping the landscape of data center architectures. As organizations increasingly adopt 100G transceivers, these devices become a significant part of network construction costs. Notably, over 90% of optical fiber links in small and medium-sized data centers, and more than 70% in larger facilities, are less than 100 meters in length. This trend underscores the relevance of multimode fibers, which can effectively support most of these connections. Within the 100G spectrum, the QSFP28 multimode modules, specifically QSFP 100G SRBD, and QSFP 100G SWDM4, offer compelling solutions tailored to meet the diverse needs of modern data centers. This comparison explores the features, advantages, and application scenarios of these two prominent transceivers.

Introduction of QSFP 100G SRBD and QSFP 100G SWDM4

As network demands continue to grow, the 100GBASE-SRBD and 100GBASE-SWDM4 optical modules have emerged to meet the challenges of modern data centers regarding bandwidth, transmission distance, and efficiency. These two modules not only deliver outstanding performance but are also optimized for different application scenarios, ensuring reliable and efficient data transmission. Next, we will briefly explore the fundamental information about these two modules.

QSFP 100G SRBD

The QSFP 100G SRBD is a 100G optical transceiver designed for short-range data center applications, particularly in high-density environments requiring bidirectional data transmission. The term SRBD stands for "Short Range Bidirectional," where SR refers to short-range transmission and BD indicates bidirectional communication. This module's ability to transmit and receive data over a single multimode fiber makes it highly efficient for optimizing port usage in network equipment.

Basic Transmission Method:

  • Fiber Type: Designed to utilize a single multimode fiber.

  • Wavelength Division Multiplexing (WDM): Simultaneously transmits and receives optical signals over two distinct wavelengths (850 nm and 900 nm) through its dual LC ports.

  • Laser Type: Employs a dual-wavelength Vertical-Cavity Surface-Emitting Laser (VCSEL) bidirectional optical interface, specifically optimized for Pulse Amplitude Modulation with four levels (PAM4) signaling.

Application Scenarios:

  • Transmission Distance: Supports distances of up to 70 meters with OM3 fiber, 100 meters with OM4 fiber, and an impressive 150 meters with OM5 fiber.

  • Data Center Applications: Ideal for short-range data center applications, especially in environments requiring high-density and reliable data transmission.

QSFP 100G SWDM4

The QSFP 100G SWDM4 transceiver is another 100G optical module, designed for short-range data center applications that require optimizing existing multimode fiber infrastructure. SWDM4 stands for "Short-Wavelength Division Multiplexing 4," indicating that this module uses four channels for transmission, each on a distinct wavelength within the short-wavelength spectrum.

Basic Transmission Method:

  • Fiber Type: Similar to the 100G QSFP28 SR BiDi module, it uses duplex LC interfaces.

  • Wavelength Division Multiplexing (SWDM): Facilitates the simultaneous transmission of optical signals across four distinct wavelength bands (850nm, 880nm, 910nm, and 940nm) over a single multimode fiber core.

  • Technology Implementation: Cleverly utilizes MUX/DMUX technology, allowing for multi-wavelength transmission that maximizes the capacity of the optical link and enhances overall network performance without requiring additional fiber infrastructure.

Application Scenarios:

  • Transmission Distance: Effectively transmits data up to 70 meters when using OM3 fiber patch cables and extends to 100 meters with OM4 fiber patch cables.

  • High-Density Data Center Applications: Particularly well-suited for high-density data center applications, where optimizing existing multimode fiber systems to support increasing data demands is critical.

Working Principle of QSFP 100G SRBD and QSFP 100G SWDM4

QSFP 100G SRBD

The operational principle of the 100GBASE-SRBD module is based on the simultaneous transmission and reception of data over different wavelengths, effectively doubling the data capacity of a single fiber. This capability enhances network performance significantly, ensuring efficient data flow across various multimode networking environments. The design reduces the need for additional fiber infrastructure and simplifies network deployments while maintaining robust performance standards essential for modern data centers. The working principle of the 100GBASE-SRBD module is as follows:

100G modules

QSFP 100G SWDM4

The 100GBASE-SWDM4 module also utilizes duplex LC interfaces, but it enhances data transmission capabilities by implementing MUX/DMUX technology for Short-Wavelength Division Multiplexing (SWDM). This allows for simultaneous transmission of optical signals across four distinct wavelengths—850 nm, 880 nm, 910 nm, and 940 nm—over a single multimode fiber core. The SWDM4 module supports transmission distances of up to 70 meters with OM3 fiber and 100 meters with OM4 fiber, making it particularly well-suited for high-density data center applications where optimizing existing multimode fiber systems to meet increasing data demands is crit. This makes the SWDM4 module particularly well-suited for high-density data center applications, where optimizing existing multimode fiber systems while supporting increasing data demands is critical.

The module design allows seamless integration into current network environments, providing a cost-effective solution for upgrading infrastructure and ensuring compatibility across various multimode systems. The operational principle of the 100GBASE-SWDM4 module is as follows:

100G modules

When Should Each Transceiver Be Used?

The 100G-SWDM4 transceiver uses four wavelengths (850nm, 880nm, 910nm, 940nm), while the 100G-SRBD transceiver uses two (850nm and 900nm). This difference gives the SWDM4 higher spectral efficiency, making it suitable for high-density applications. Despite the SRBD transceiver's lower insertion loss and better tolerance to modal dispersion, SWDM4’s efficiency makes it ideal for maximizing fiber utilization.

In terms of reach, SWDM4 supports 70 meters over OM3 and 100 meters over OM4 MMF. On the other hand, SRBD offers up to 150 meters of OM5 fiber. SWDM4 is optimized for existing OM3 and OM4 deployments, while SRBD can use OM5 for extended reach.

Both transceivers use the QSFP28 form factor with LC connectors, but SWDM4 stands out in power efficiency and space savings, making it a good choice for modern data centers. While SRBD supports both 100G and 40G ports, SWDM4 is specifically tailored for 100G applications.

Although they are widely used and compatible with OM3/OM4 duplex MMF, SWDM4 and SRBD are not interoperable. For future 400G compatibility, SRBD should be preferred, as it supports breakout connections with 400G optics. SWDM4 lacks this interoperability with 400G optics.

In summary, the choice between SRBD and SWDM4 depends on your needs: SRBD for future 400G compatibility and extended reach with OM5, and SWDM4 for high-density and efficient use of existing OM3/OM4 infrastructure.

Product Specification
QSFP 100G SRBD
QSFP 100G SWDM4
Wavelength
Dual wavelengths (850nm and 900nm)
Four wavelengths (850nm, 880nm, 910nm, 940nm)
Maximum Transmission Distance
100m (OM4 Fiber)
150m (OM4 Fiber)
Fiber Type
Multimode Fiber (OM3/OM4)
Multimode Fiber (OM3/OM4)
Connector Type
LC Duplex Connector
LC Duplex Connector
Signal Modulation
Short Reach Bidirectional
Short Wavelength Division Multiplexing
Optical Module Power Budget
Lower Power Budget (suitable for short distances)
Higher Power Budget (suitable for longer distances)
Optical Module Power Budget
Lower power budget (suitable for short distances)
Higher power budget (suitable for longer distances)
 

Conclusion

As you evaluate the best solutions for your data center, FS offers a comprehensive range of high-quality 100G optical transceivers, including the QSFP 100G SRBD and QSFP 100G SWDM4 modules. Each transceiver is engineered to meet the demands of modern networks, ensuring seamless integration, exceptional performance, and energy efficiency. Whether you're looking to optimize your existing multimode fiber infrastructure or planning for future scalability, FS provides the expertise and products to support your network's growth. Explore our product offerings and find the ideal transceiver for your needs at FS.com.

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