1. Definition of 100G QSFP28

100G QSFP28 (or 100 Gigabit Quad Small Form-Factor Pluggable 28) is a series of high-speed optical modules designed for data communication and networking applications. The full name QSFP28 stands for Quad Small Form-Factor Pluggable Plus 28, meaning it is a four-channel small pluggable module. Each channel can achieve a rate of up to 28 Gbps. These optical modules are widely used in data centers, telecommunications networks, and other high-bandwidth environments to support the rapid exchange of large amounts of data over short and long distances. The form factor of QSFP28 ensures compatibility with various network devices, making it a popular choice for network administrators and operators looking to meet modern high-performance networking demands.

2. Standards for QSFP28 100G Optical Modules

The standards for 100G QSFP28 optical modules are primarily defined by two organizations: IEEE and the Multi-Source Agreement (MSA). IEEE specifies the standards for QSFP28 SR4, QSFP28 LR4, and QSFP28 ER4. From their names, "QSFP" refers to the form factor, "28" indicates a maximum transmission rate of 28 Gbps per channel, "SR" stands for short range with a transmission distance of 100 meters, "LR" stands for long range with a distance of 10 kilometers, and "ER" represents extended range with a distance of 40 kilometers. The number "4" in ER4 signifies that the module has four channels. For example, the QSFP28 LR4 is a long-range 100G module capable of transmitting 100G signals over four wavelengths, with a transmission distance of 10 kilometers.

The most commonly used 100G optical modules defined by IEEE are 100GBASE-SR4 and 100GBASE-LR4. However, the transmission distance of the QSFP28 SR4 may be limited and may not meet all interconnect requirements, while the cost of the QSFP28 LR4 module can be high for large data centers. Therefore, the MSA introduced mid-range connection solutions and defined the standards for QSFP28 PSM4 and CWDM4 modules. While the QSFP28 100G LR4 module can cover the capabilities of the QSFP28 CWDM4, the QSFP28 100G CWDM4 solution is more cost-effective and competitive for transmission distances of up to 2 kilometers.

3. Types of Lasers for QSFP28 100G

Laser technology is critical for the functionality of 100G QSFP28 transceivers, which come in five main types: VCSEL, FP, DFB, DML, and EML. These lasers exhibit unique characteristics in terms of operating wavelength, mode, and suitable operating environments.

4. Applications of QSFP28 100G Optical Modules

QSFP28 100G optical modules have a wide range of applications in high-speed data communication networks. Some common applications include:

• Data Centers: QSFP28 optical modules are frequently used in data centers to meet the high-speed connection demands of modern cloud computing, storage, and virtualization environments. They are used to interconnect switches, routers, and servers within data centers.

• Enterprise Networks: These optical modules are suitable for enterprise networks, enabling high-speed data transmission and supporting tasks such as network aggregation, data backup, and interconnecting various network devices.

• Telecommunications: In the telecommunications industry, QSFP28 optical modules are used for high-capacity connections, whether for short-range or long-range transmissions, making them essential for the deployment of 100G networks.

• Service Providers: Service providers use QSFP28 optical modules to meet the growing demand for high-bandwidth services (such as 100G Ethernet) within their networks. These optical modules can be utilized in metropolitan and long-haul networks.

• High-Performance Computing (HPC): HPC clusters and supercomputers require high-speed data links to handle complex computations. QSFP28 optical modules provide the necessary bandwidth for rapid data transfer in HPC environments.

Frequently Asked Questions

1. How to choose the best 100G QSFP28 optical module?

For distances of 5 to 100 meters, the QSFP28 SR4 optical transceiver can be selected. When using OM3 fiber, data can be effectively transmitted up to 70 meters; with OM4 fiber, transmission can extend to 100 meters.

If the transmission requirement is between 100 meters and 2 kilometers, it is advisable to consider the suitability of QSFP28 100G PSM4 or QSFP28 CWDM4 modules. Notably, while QSFP28 CWDM4 is significantly more expensive than QSFP28 PSM4, it has the advantage of utilizing only two single-mode fibers for bidirectional transmission, which is much more cost-effective compared to the MPO single-mode cabling required for QSFP28 PSM4. Therefore, the overall cost of implementing QSFP28 100G PSM4 may increase significantly. The decision to choose between QSFP28 PSM4 and QSFP28 CWDM4 should be based on the specific interconnect distance.

For transmission distances of 10 to 40 kilometers, the QSFP28 100G LR4 can be used, with a maximum transmission range of 10 kilometers. The QSFP28 ER4 optical module can achieve even longer distances, with a maximum transmission capability of 40 kilometers.

2. Can 100G QSFP28 modules connect downwards?

Yes. 100G QSFP28 modules can connect with 25G optical modules and 10G optical modules, such as 100G to 4x25G optical modules or 100G to 10x10G optical modules. Connection is made using branch fiber cables.

3. Are 100G QSFP28 optical modules compatible with various network device manufacturers?

In general, the design of 100G QSFP28 modules follows industry standards set by organizations like IEEE (Institute of Electrical and Electronics Engineers), ensuring a degree of compatibility among different network device manufacturers. This means that, theoretically, 100G QSFP28 modules should be compatible with a variety of network devices from different manufacturers.

4. What power consumption considerations are there for 100G QSFP28 modules?

Factors influencing the power consumption of 100G QSFP28 modules include module type, operating mode, link length, data rate, standby mode, cooling, power budget, data center efficiency, and future readiness. Efficient power management is crucial for optimizing performance and reducing operational costs.

5. What types of optical connectors are used with 100G QSFP28 modules?

100G QSFP28 modules typically use LC duplex or MTP/MPO connectors for optical connections. LC duplex connectors are used for single-mode or multimode fiber connections, while MTP/MPO connectors are commonly used for high-density multimode fiber connections, especially in data center environments. The choice of connector depends on the specific application and cabling infrastructure.