Everything You Should Know About 100G Optical Transceiver

With the development of data centers, more and more data centers are facing the problem of upgrading their network infrastructure. Most data centers are considering upgrading to a 100G Ethernet network, and 100G will become the mainstream trend for future network development. The demand for 100G optical transceivers in the communications industry is also increasing. There are many types of 100G optical fiber transceivers, including several models of CXP, CFP, and QSFP28. Before you buy or design a solution, you should understand the types and characteristics of these different 100G optical fiber transceivers. This article will introduce the 3 models of CXP, CFP, and QSFP28 in detail, as well as the common 100G optical transceiver connector.

What is the 100G Standard?

The more common 100G interface standards are SR4(Short Reach), SR10, LR4(Long Reach), ER4, and ZR4. All these standard electrical signals are defined as 1010G. For LR4 and ER4, the external optical signal is 425G. Among these models, SR4 and SR10 are mainly used for short-distance data transmission, and their maximum transmission distance supports 100 meters. While LR4, ER4, and ZR4 are usually used for long-distance transmission. The maximum transmission distance of LR4 is 10km, the maximum transmission distance of ER4 is 40km, and the maximum transmission distance of ZR4 is 80km.

100G Optical Transceiver Types

The mainstream 100G optical transceiver models currently available in the market include CXP optical transceivers, CFP/CFP2/CFP4 optical transceivers, and QSFP28 optical transceivers. The most popular optical transceiver model in the market is the QSFP28 optical transceiver now.

CXP Optical Transceiver

The letter C in CXP stands for 12, which uses a hexadecimal notation. The 12 means that the CXP module is a 12 full-duplex channel optical module, designed with 12x10G transceivers, it has 12 transmit channels and 12 receive channels, and it can provide transmission rates up to 120G. The CXP transceiver is easy to implement, supports hot-plugging, and has a smaller form factor size than the CFP. It supports 100GBASE-SR10 multimode short-range transmission and is interchangeable with CFP/CFP2/CFP4 and QSFP28 optical transceivers under the SR10 standard. The maximum transmission distance of the CXP 100G optical module supports 100m via OM3 cable, and 150m via OM4 cable. Data center networks, high-performance computing networks, enterprise core aggregation, and service provider transport applications.

Figure 1: 100G CXP Transceiver 

CFP Series Optical Transceiver (CFP / CFP2 / CFP4)

100G CFP optical transceiver is a very large size and pluggable optical transceiver, where the letter C is a Roman numeral representing the number 100 (centum). The size of CFP and CFP2, CFP4 optical transceiver is different, CFP2 is half the size of CFP, and CFP4 optical transceiver is half the size of CFP2 and can support 40/100G. CFP4 optical The width and power consumption of the CFP4 transceiver is vastly improved over the previous two generations because of its smaller size, and it is also more suitable for 100G Ethernet, which requires higher density.

Figure 2: 100G CFP Transceiver 

QSFP28 Optical Module

The 100G QSFP28 optical module stands for Quad Small Form-factor Pluggable, it is designed to have four independent transmission channels, each channel has a transmission rate of 25G, and the aggregation is a 100G transmission rate. 100G QSFP28 has a smaller form factor than CFP4 optical modules, which has significant advantages for high-density data transmission. At present, the mainstream QSFP28 optical modules on the market include 100GBASE-PSM4, 100GBASE-SR4, 100GBASE-LR4, and 100GBASE-CWDM4. As 100G QSFP28 optical modules become more and more popular in the market and the technology matures, their cost will increase. The lower is the best choice for most future data centers.

Figure 3: 100G QSFP28 Transceiver

Different Types of 100G Optical Transceiver Connectors

The most common types of connectors in 100G optical modules are SC / LC / MPO and others. In the traditional 10G interface, SC/LC connectors are usually used to form dual-core interconnect single-income hairs. LC and SC connectors use a very similar structure and principle, but the LC connectors have a smaller size.

The MPO connector is a multiple fiber push-on / push-off all-in-one form adapter. This connector uses parallel technology, multiple transponders are designed into the same box, and they are combined together by multiple optical fibers. composition. There are two common MPO models on the market: MPO12 and MPO24.

MPO12 has 12 optic cores, four of these are receivers, another four are transmitters, and the remaining four are vacant fibers. These 12 fibers contain 4 idle, so this standard is SR4/LR4.

MPO 24 is defined as a 24-core, 12-wire, 12-wire, 24-wire welded 12-core fiber array. One of the fibers is used for the transmitter and the other fiber is used for the receiver. When it is used for CFP 100G optical module, in an array, the middle 10*10G fiber is used to transmit traffic, and the outermost two fibers are idle. There are a total of 4 fibers idle in both arrays, so it's formatted as SR10. When it's used for a CXP module, there are 12 transmit fibers and 12 receive fibers, and no idle lines.

In the case of the QSFP28 100G optical module, for example, if the transceiver uses a splitter and multiplexer internally to modulate 4 channels of 28G data to the optical fiber, and the external transceiver is a single payload single LC interface, which saves a lot of fiber resources when applied to long-distance transmission. This multi-fiber fiber optic transmission technology is WDM, which is widely used in the construction of 5G base stations. MPO connectors are usually used for short-distance transmission, while for long-distance transmission, LC connectors are used to save fiber.

Can Different 100G Optical Transceivers Interconnect?

100G optical transceivers of the same type can interconnect with other modules. For instance, a CXP can be interconnected with a CXP, a CFP-SR10 can be interconnected with a CFP-SR10. When communication needs to be established between different types of 100G transceivers they need to be of the same standard and interface type. Another example, the CFP / CFP2 / CFP4 can transmit with the QSFP28 under the same signaling system and interface type. CFP2-LR4 with a duplex LC interface can communicate with QSFP28-LR4 under a duplex LC interface. The 100G CXP transceiver can only interconnect with the CFP/CFP2/CFP4/QSFP28 optical transceiver when the SR10 standard is used. When interconnecting the CXP module and CFP2-SR10 module, CXP must mask off 1, 12, 13, and 24 at the edge of CXP, since CXP is a 12-channel transceiver and CFP2 is a 10-channel transceiver.

Conclusion

Most data centers now prefer to update their networks to 100Gbps Ethernet. Before upgrading your network, you must know all about these 100G optical modules. The 100G CXP transceiver is gradually phased out of the market today and is only considered by engineers in a few special cases, with 100G CFP transceiver and 100G QSFP28 optical modules becoming the mainstream in the market. Choose with 100G optical transceiver to update your network in QSFPTEK, we can provide you with a variety of optical modules including cost-effective and high-quality 100G CFP and QSFP28 optical modules. Contact us via sales@qsfptek.com.