It’s known that QSFP28 optics play a key part in current 100G Ethernet, in which 2 km 100G QSFP28 CWDM4 stands out. To some degree, its appearance satisfies the requirements for both low cost and long transmission distance in the data center. Today, this article will have an introduction to 100G QSFP28 CWDM4 in these aspects, such as CWDM4 MSA, CWDM4 definition as well as advantages and applications of 100G QSFP28 CWDM4 by Gigalight.
What’s CWDM4 MSA?
The CWDM4 MSA (Multi-Source Agreement) targets a common specification for low-cost 100G optical interfaces that run up to 2km in data center applications. The MSA uses CWDM technology with 4 lanes of 25Gbps optically multiplexed into and demultiplexed from a duplex single-mode fiber. CWDM4 MSA targets the broad data center 100G interconnects that support FEC applications.
CWDM4 MSA’ members consist of Avago Technologies, Finisar Corporation, JDSU and Oclaro, Inc. The Multi-Source Agreement (MSA) defines 4 x 25Gbps Coarse Wavelength Division Multiplex(CWDM) optical interfaces for 100Gbit/s optical transceivers in Ethernet applications including 100GbE. Forward error correction (FEC) is required to be implemented by the host in order to ensure reliable system operation. Two transceivers communicate over single mode fibers(SMF) of length from 2 meters to at least 2 kilometers. The transceiver electrical interface is not specified by this MSA but can have four lanes in each direction with a nominal signaling rate of 25.78125Gbps per lane.
Different form factors for the transceivers are possible. Initial implementations are expected to use the CFP4 or the QSFP28 module form factors. Other form factors are possible and are not precluded by this MSA.
What’s CWDM4 Optical Transceiver?
The 100G QSFP28 CWDM4 optical transceiver is a full duplex, photonic-integrated optical transceiver module that provides a high-speed link with a maximum transmission distance of 2km for 100G Ethernet. CWDM4 interfaces with LC duplex connectors. It uses 4×25Gbps to achieve 100Gbps. Specifically speaking, four lanes with center wavelengths of 1270nm, 1290nm, 1310nm and 1330nm are controlled on the transmit side. On the receiving side, four lanes of optical data streams are optically de-multiplexed by an integrated optical demultiplexer. With an optical multiplexer and de-multiplexer, one just uses a duplex single-mode fiber to connect two 100G CWDM4 optical transceivers. CWDM4 has many advantages, such as low power consumption, high compatibility, Digital Diagnostic Monitoring (DDM) support and so on. Nowadays, it has been widely applied in Local Area Network (LAN), Wide Area Network (WAN), and Ethernet switches and router application.
Advantages and Applications of 100G QSFP28 CWDM4
CWDM4 has many advantages, such as low power consumption, high compatibility, Digital Diagnostic Monitoring (DDM) support, high transmission rate, long transmission distance and so on, in which the long transmission distance is its most highlighted feature. It adopts WDM (Wavelength Division Multiplex) tech, full-duplex LC connector, and single-mode fiber, which are helpful to realize 2km reaches. Besides, on account of the adoption of WDM, it just needs two single-mode fibers to realize the transmission, which, to some degree, save the costs in fibers. At this time, compared with QSFP28 PSM4 in cost and transmission distance, QSFP28 CWDM4 is preferred.
As for its applications, by virtue of its various advantages, it’s widely utilized in many fields, such as CATV(Community Antenna Television), FTTH(Fiber To The Home), 1G and 2G fiber channel, Gigabit Ethernet, SONET (Synchronous Optical Network) OC-3（155Mbps）/OC-12（622Mbps）/ OC-48（2.488Gbps） , Security and Protection systems; also in Local Area Network (LAN), Wide Area Network (WAN), and Ethernet switches and router application.
Seen from the general introduction, it seems that QSFP28 CWDM4 optical transceiver is high in cost, and it is still a cost-effective solution for long distance transmission, on account that it can help to save the cost in amounts of fiber cables and to offer 2km reaches. Maybe it will get improved with the progress in technology.