Both the 100G LR and LR4 support a maximum transmission distance of 10km over single-mode fibre (SMF) typically using duplex LC connectors. They adhere to IEEE standards which ensures interoperability regardless of vendor. The "LR" in 100G LR stands for "Long Reach," indicating their suitability for long-distance applications, such as connecting data centers or telecommunication networks. The 100G QSFP28 LR4 is a widespread 100G QSFP28 optical module. The 100G QSFP28 LR4 optical transceiver can convert four 25Gbps. CWDM4 transceivers are designed for data centers and enterprise networks that require moderate to high data rates over moderate distances. They operate using coarse wavelength division multiplexing, which allows multiple wavelengths (or channels) to be combined and transmitted over a single fiber. SR (Short Range): Up to 300 meters, using multimode fiber for. There are various types of QSFP-DD optical modules for 2km-10km transmission. The main focus is on four models: FR4/FR8 (2km) and LR4/LR8 (10km). It is commonly used for data center interconnect (DCI), campus backbone, and aggregation layers where reliable 100G.
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