100GBASE-LR4 vs. Single Lambda 100GBASE-LR, What’s the Difference?
100G QSFP28 optical transceivers have become an integral and core component of data centres, enterprise networks and telecommunication infrastructures. With a wide range of QSFP28 100G optical modules available, you may be wondering what is the difference between 100GBASE-LR4 and Single Lambda 100GBASE-LR. While they both support long-haul transmission and provide high bandwidth, there are significant differences in their technical implementations, among other things. This article will delve into the key differences between these two types of 100G optical modules (100G LR1 and 100G LR4) to help you make a more informed decision when choosing the right optical module.
What is 100G QSFP28 LR4 Transceiver?
The 100G QSFP28 LR4 is a widespread 100G QSFP28 optical module. It adopts the QSFP28 form factor, NRZ modulation, and duplex LC connectors. The transmission distance can reach 10 km when paired with OS2 duplex fiber patch cables. The 100G QSFP28 LR4 optical transceiver can convert four 25Gbps electrical signals into four LAN WDM optical signals and then multiplex them in a single channel for transmission. At the receiving end, the transceiver can demultiplex the multiplexed 100G optical input signal into 4 LAN WDM optical signals and then convert them into four electrical output signals. Ideal for data center interconnects, network service provider infrastructure and enterprise infrastructure, and other high-bandwidth applications.
What is QSFP28 100G Single Lambda LR Transceiver?
Before understanding what a 100G Single Lambda LR module is, we need to first understand what a 100G Single Lambda is. 100G Single Lambda is a widely used optical specification based on PAM4 modulation.
The currently popular 100G optical standards, such as 100G SR4, 100G LR4, 100G CWDM4, 100G PSM4, 100G ER4 optical modules, etc., all rely on four 25G optical channels for transmission in parallel or wavelength division multiplexing, and they all require a series of expensive optics and packaging. In order to reduce costs and increase transmission rates, the industry has proposed the 100G single-lambda specification. Optical modules that follow this specification use single-wavelength 100G PAM4 modulation.
The QSFP28 100G Single Lambda LR optical module is a product based on this technology. These optical modules are usually deployed on single-mode fiber (SMF) and have transmission distances up to 10 kilometers. "LR" stands for "Long Reach," indicating that it is also suitable for long-distance transmission applications, such as connecting data centers or telecommunications networks in MANs.
The Similarities of 100G LR and 100G LR4 Transceiver Modules
Fiber Type
These two QSFP28 100G optical modules use duplex OS2 fibers for data transmission.
Interface Type
Both use duplex LC connectors to connect single-mode fibers.
Standardization
Both the 100G LR and 100G LR4 optical modules are compliant with IEEE standards, ensuring device interoperability between different vendors.
Transmission Distance
Both Single Lambda 100GBASE-LR and 100GBASE-LR4 optical modules support a transmission distance of 10 kilometers and can meet various long-distance data transmission needs.
QSFP28 100G LR4 vs. Single Lambda 100G QSFP28 Modules, What's the Difference?
Both QSFP28 100G LR4 and Single Lambda 100G QSFP28 optical modules play important roles in optical communications, but they have significant differences. The following table compares the key features of the two to help us understand their differences more intuitively.
100G QSFP28 LR4 NRZ vs. PAM4 QSFP28 LR Modules, How to Choose?
When choosing between 100G LR and 100G LR4 modules, the first thing you need to consider is the performance requirements. 100G LR4 offers a higher signal-to-noise ratio (SNR) through the use of NRZ modulation with four 25G channels and is more suitable for environments where fewer errors are required, especially in scenarios where cost-effectiveness is a key requirement. 100G LR, on the other hand, is more suitable for applications that require higher data rates and maximise bandwidth efficiency and is particularly suited to high-density data environments such as data centres, although it faces certain challenges in terms of signal processing complexity and SNR.
Next, consider network infrastructure and device compatibility. Confirm which types of optical modules are supported by existing equipment (e.g., switches, routers). Some devices may only support specific types of modules or limited transmission rates, so it is necessary to check whether the new module is compatible with the physical and protocol interfaces of existing network devices to ensure proper interoperability.
Finally, cost and future scalability are factors that should not be overlooked when making a selection. Compare the cost of the modules, including initial procurement costs and long-term operating costs, and consider the need for future upgrades and the associated costs. Also, consider the solution's future scalability. 100G LR has better compatibility when migrating to 400G, which helps in long-term planning.
Conclusion
In summary, 100GBASE-LR4 and Single Lambda 100GBASE-LR transceivers play an important role in data centers, telecom networks and enterprise infrastructure, supporting high-bandwidth long-distance transmission. The main difference between them is the transmission technology. 100G LR4 optical transceiver uses four wavelengths, NRZ modulation, and the design is more complex. The 100G single-wavelength optical transceiver uses 100G PAM4 modulation. The design of single-wavelength technology is simpler and the optical components count is greatly reduced. When selecting, performance requirements, network infrastructure compatibility, cost considerations, and future scalability are all key factors in the decision. Understanding your network needs will help select the most appropriate optical module to ensure optimal performance and future scalability.
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