With the upgrade of the network from 10G/25G to 100G, 100G Ethernet begins to prevail in the optical communication industry. After that, various solutions appear for 100G Ethernet, in which CFP series and QSFP28 series optical transceiver are regarded as the two main solutions. However, by comparison, QSFP28 series is seemingly preferred by most data center users for the upgrade of 100G on account of the cost, transmission distance, etc.
A Basic Introduction to QSFP28 Optics
The QSFP28 optical module provides four channels with different signals(supporting the data transmission mode of 4 x 25G), and the transmission rate is increased from 25Gbps to 40Gbps. The size of the QSFP28 optical module is smaller than the other 100G modules, so more attention has been paid to it. If one wants to deploy a high-density and high-speed network,100G QSFP28 optical module will be a good choice.
What Are the Main Types of QSFP28 Optical Module?
Based on different IEEE (Electrical and Electronic Engineer Association) or MSA(Multi-Source Agreement) standards, the QSFP28 optics solution can mainly provide four types as follows:
1. 100G QSFP28 CWDM4 Optics
The transmission distance of 100G QSFP28 CWDM4 optical module can reach 2km, and the coarse wave multiplexing tech is used to transmit. It uses CWDM tech to reduce the initially-used 8 optical fibers for data transmission to 2 optical fibers. But the cost of QSFP28 CWDM4 optical module is much higher than that of 100GBASE-PSM4 QSFP28. If one needs a cost-effective optical module for long-distance transmission, the 100GBASE-PSM4 QSFP28 can be chosen for the 100G network upgrade.
2. 100G QSFP28 PSM4 Optics
100G QSFP28 PSM4 is a standard defined by MSA, with a transmission distance of 500m. It is with high speed and low power consumption, generally used in 40G and 100G Ethernet. The QSFP28 PSM4 optical module has a digital diagnosis function, the interface type is MTP/MPO. The band fiber with the MTP/MPO connector can be inserted into the QSFP28 optical module. If one has requirements for high speed and low power consumption, it is recommended to use this optical module to upgrade the 100G network.
3. 100G QSFP28 LR4 Optics
100G QSFP28 LR4 is mainly used in the transmission applications of multimode fiber, and the transmission distance of the optical module can reach 10km. The 100GBASE-LR4 QSFP28 optical module converts the 4x25Gbps electrical signal to 4 LAN WDM optical signals and then multiplexes it as a single channel to achieve 100G optical transmission. If one needs an optical module for long- distance transmission, QSFP28 LR4 optical module can be chosen for the 100G network upgrade.
4. 100G QSFP28 SR4 Optics
The transmission distance of 100G QSFP28 SR4 can reach 100m. The interface type is MTP/MPO, usually used with OM3 fiber and OM4 fiber. The QSFP28 full duplex optical module provides 4 independent transmitting and receiving channels at a rate of 25Gbps per channel to reach 100Gbps. If one needs an optical module for short-distance transmission,100GBASE-SR4 QSFP28 can be selected to upgrade the 100G network.
To sum up, QSFP28 optics can meet various requirements for transmission distance, cost, power consumption, form factor. Therefore, QSFP28 optical transceivers are the right suitable solution for the upgrade of the 100G network. With respect to which one the most cost-effective solution is, it is up to one’s specific demands.
Why 25G Ethernet Switches Are Still Necessary?