Revolutionizing Access and Edge Networks with QSFP28 100ZR Coherent Tunable DWDM Transceivers

As bandwidth demands continue to surge across telecommunications and broadband networks, operators are increasingly seeking cost-effective, high-performance solutions that can meet both current and future needs. The availability of 100ZR coherent tunable DWDM (Dense Wavelength Division Multiplexing) transceivers in a QSFP28 form factor marks a significant milestone in this quest, offering a powerful, pluggable solution for access, edge, and metro networks. 

What Makes the QSFP28 100ZR Unique?

The QSFP28 100ZR Coherent Tunable DWDM Transceiver (TQSFP28-ZR) is a game-changer for network operators who need to maximize capacity without incurring the high costs traditionally associated with long-distance DWDM solutions. Table 1 below shows a comparison of the various solutions available to provide 100G service beyond 10km.

Table 1 Comparison of 100G Solutions Beyond 10km

Traditional transport systems come with high overall cost and power consumption. Plus, you need specialists to do the install–usually the network equipment manufacturer—and the installation time is quite long.    

In the case of the CFP2-DCO (Digital Coherent Optics), the port density per 1RU (typically 4-8 ports per RU) is way lower compared to QSFP form factors which can typically host 30-36 interfaces per RU.  

The QSFP28 PAM4 fixed DWDM transceiver is probably the closest option to the QSFP28 100ZR since it has the QSFP28 form factor.  However, this solution is only for fixed DWDM channels and network engineers would still need to install some sort of external amplification and dispersion compensation modules to reach more than 1-2km. 

Traditional 100G ER4/ZR4/EZR4 Gray and 100G BiDi optics offer lower cost/power/complexity but are non-DWDM solutions.    

Finally, 400G coherent ZRx modules can be downrated to be used 1x100G applications which might not be ideal as it is using only 25% of the host port capacity. Most importantly, QSFP-DD/OSFP transceivers require newer host switches/routers to support this new technology, meaning a lot of investment upfront in all new equipment.   

The QSFP28 form factor has been, by far, the most deployed form factor over the last decade for 100G transmission. 

“The closer you get to the Access network – the more cost effective you need to be” commented Precision OT Principal Solutions Engineer Pol Torres. “Any time you can reuse installed equipment like existing switches/routers with QSFP28 interfaces and be able to repurpose them to upgrade data connections, it’s a win.” 

Unlike the 400G ZRx coherent pluggable QSFP-DD (or OSFP) which has had a more gradual integration into the market due to the extra initial investment involved, the TQSFP28 100ZR can reuse existing equipment and ports (provided they can accommodate the higher power requirements and additional heat dissipation), bypassing the need to invest in new equipment or SW licenses. 

TQSFP28 100ZR Tunable DWDM Transceiver Overview

The 100ZR product line of 100G transceivers are capable of reaching 80 km on DWDM unamplified links or up to 300km on DWDM amplified links. The standards below have been applied to larger form factors such as CFP2 and QSFP-DD. The new, groundbreaking 100ZR technology also falls within these established standards, filling a gap in the industry which has long awaited a tunable, QSFP28 100G DWDM edge solution that does not require expensive transport equipment or new higher cost switches and routers.

100ZR Standards: 

• The IEEE 802.3ct-2021 is an IEEE standard amendment. It specifies the physical layer parameters for transmitting 100Gb/s Ethernet signals using DWDM technology, which allows multiple data streams to be carried simultaneously on a single fiber at different wavelengths. 

• The ITU-T G.698.2 is an International Telecommunication Union (ITU) standard that defines optical parameter values for DWDM systems. 

TQSFP28 100ZR Applications: 

The TQSFP28 100ZR is ideally suited to provide Access/Edge networks with 100G data rates in DWDM or grey links network designs for long distances. Applications may include 5G backhaul/fronthaul, business customers, primary to secondary hub connections, etc.  

Similar to 400G ZRx implementations, this solution will allow a shift towards IPoDWDM in the Access/Edge/Metro networks and a reduced need for expensive and long time to deploy full Transport solutions.  

The primary applications will be: 

• Point to point unamplified grey links up to 80-120 km (TX output power dependent) 

• Point to point unamplified DWDM links up to 30-80 km (TX + MUX-dependent / Insertion Loss) 

• Point to point amplified DWDM links up to 120km (with default CD reach) 

• Point to point amplified DWDM links up to 300km (with extended CD reach) 

In the Access/Edge space, we expect up to 80km to cover 90% of the use cases. 

Figure 1 Optical Access/Edge Network Schematic

The TQSF28 100ZR technology is not a “one size fits all”. To reap the full benefits of the technology and integrate it successfully into your network, one or more product customizations may be desirable to ensure optimum network performance. Reach out to us to learn more about TQSFP28-ZR and related coherent technology.