2017-12-13

How Much Do You Know about QSFP28 CWDM4?

These years data center has always been expanded at the high speed and higher rate of single port are required, which contributes to the wide applications of 100G in the data center. While in the practical use, many optical transceiver usually can’t meet the demands on the deployment of data center by the way of saving cost, on account of the variety  in the lengths of optic fiber channel. For it, 2 km 100G QSFP28 CWDM4 appears in the current optical components market. Well, this article will have an introduction to QSFP28 CWDM4  from perspectives of CWDM4 definition, CWDM4 MSA as well as advantages and applications of QSFP28 CWDM4 by Gigalight.

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.

100G QSFP28 CWDM4


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 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.

Advantages and Applications of 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-3155Mbps/OC-12622Mbps/ OC-482.488Gbps , Security and Protection systems; also in Local Area Network (LAN), Wide Area Network (WAN), and Ethernet switches and router application.

Conclusion
Although CWDM4 transceiver is high in cost, and the it’s still an economical solution for long transmission distance. Whether in aspects of link’ lengths or cost savings, it can meet the needs in a cost-effective way by DWM. Maybe it will get improved with the advances in future tech. We will see.


Note: article resource from www.gigalight.com