What is Difference ?: 100G LR vs LR4
When exploring our 100G QSFP28 optical products, you might find yourself wondering, what is the difference 100G LR vs 100G LR4? (Although technically correct would be LR1 vs LR4). Is the LR4 a groundbreaking fourth-generation technology in telecommunications, offering a significant breakthrough, yet somehow more affordable than the seemingly older LR module? In this concise article, we’ll clarify these differences, explain their implications, and guide you on how to use them effectively.
A Journey Through History
Our story begins in 2010 with the IEEE’s release of the 802.3ba standard, the first optical standard for 100G modules, which includes 100GBASE-LR4. This innovation enabled new speeds by compressing 25G NRZ (Non-Return-to-Zero) signals into four channels—a significant step up from the then-leading 25G SFP28 modules. Simply put, 100GBASE-LR4 combines four channels of 25G SFP28 modules into a single device to achieve 100G data rates. Hence, the “4” in LR4 denotes the four-channel data stream.
Understanding 100G LR
What about 100G LR? You might have guessed it—the absence of a number before “LR” suggests a single-channel data stream. You’re correct! The 100G LR standard leverages Single-Lambda PAM4 (Pulse-Amplitude-Modulation-4-level) modulation to transmit the entire 100G data over a single channel.
NRZ vs PAM4 Modulation
The terms NRZ and PAM4 might initially seem complex. For deeper insights into these modulation techniques, explore our comprehensive article on PAM4 vs NRZ in Optical Ethernet. This resource will help you understand the technical differences, strengths, and weaknesses of both 100G standards, enhancing your purchasing decisions.
Key Differences and Applications
- 100G LR4: Utilizes NRZ modulation, providing higher signal-to-noise ratio (SNR) with four channels of 25G each. It’s ideal for scenarios requiring robust error proofing at potentially lower costs.
- 100G LR1: Employs advanced PAM4 modulation, compressing the data into a single channel for efficient bandwidth utilization. It’s suitable for applications demanding higher data rates despite reduced SNR and increased signal processing complexity.
By understanding these distinctions, telecom engineers can make informed choices about which module best fits their specific applications and operational needs.
