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The key to choosing a suitable QSFP28 100G transceiver is to find the optimal balance between transmission distance, fiber type, equipment compatibility, and budget.
Yingda has compiled the most critical selection steps and common module types, which you can refer to for decision-making.
Five step selection decision-making process
Step 1: Determine the actual transmission distance
This is the most important step. Please accurately measure the fiber link length between two device ports (including the sum of all patchcords and backbone fibers). Different distances correspond to completely different module technologies.
Step 2: Clarify the existing fiber types
Check the fiber optic patch cords and patch cables you will be using:
- Multimode fiber (MMF): typically aqua (OM3/OM4) or orange (OM2). Suitable for short distances (usually ≤100 meters) with low cost.
- Single mode fiber (SMF): usually yellow (OS2). Suitable for long distances (several hundred meters to tens of km), with better performance.
Step 3: Verify switch ports and compatibility
- Port type: Ensure that your switch port is QSFP28, not QSFP+ (40G). The QSFP28 port can be backward compatible with SFP SFP+ QSFP QSFP+ modules, but not vice versa.
- Compatibility: Confirm if the selected module is compatible with your switch brand. If the encryption function is enabled on the switch, it is usually necessary to use the original factory module, otherwise it may cause device alarms or ports to be disabled.
Step 4: Choose a plan based on the budget and scenario
Based on the distance and fiber determined in the previous steps, find the most suitable module type in the table below.
Step 5: Consider power consumption and future evolution
Power consumption: When deploying high-density, attention should be paid to module power consumption. Usually, DAC AOC cable is the lowest (<2W), SR4 is about 2-3.5W, and 100Gb LR4/ER4 is about 3.5-4.5W.
New technology: Pay attention to new modules using single wavelength 100G PAM4 technology (such as 100GBASE DR1/FR1/LR1), which have lower power consumption and may be more cost-effective.
Comparison Table of Mainstream 100G Transceiver Selection
Based on the decision results of the first four steps, you can directly refer to the following table to lock in the specific types of transceivers:
| Transmission distance | Fiber type | Recommend model | Optical interface | Typical application |
| < 5 m | Copper cable | DAC 100G | Integrated module | Lowest cost, zero latency, suitable for interconnecting devices within the same cabinet. |
| < 100 m | MMF | SR4 | MPO-12 | The absolute mainstay of short-range interconnection in data centers, with high cost-effectiveness. If the switch port density is high and the distance matches, AOC active fiber optic cable can also be selected. |
| 100-500 m | SMF | PSM4 | MPO-12 | Requires 8-core optical fiber, suitable for scenarios with abundant fiber resources. |
| 100 m-2 km | SMF | CWDM4 | Duplex LC | The mainstream DCI solution for data centers uses only 2-core optical fibers, achieving a good balance between distance and cost. |
| 2-10 km | SMF | LR4 | Duplex LC | The standards for metropolitan area networks and campus networks connect different buildings or data centers. |
| 10-40 km | SMF | ER4 | Duplex LC | Used for metropolitan core or long-distance DCI, FEC function needs to be enabled. |
| 40-80 km | SMF | ZR4 / Coherent | Duplex LC | Long distance transmission flagship solution, used for operator backbone networks or ultra long haul DCI. |
There are now single fiber bidirectional transceiver like BiDi 100G, as well as new module types such as 100G DR1/FR1/LR1 that use QSFP28 PAM4 modulation. If you have specific fiber resource limitations or want to learn about the latest technology, let’s have a deeper conversation>>>
Two key decision points
- How to choose between distance and cost? This is the most fundamental consideration.
- When the distance is within 2 kilometers, 100G QSFP28 CWDM4 is usually a more economical choice than LR4.
- Within 100 meters, the cost of QSFP 100G SR4 multimode fiber solution is much lower than any single-mode solution.
2. How to avoid compatibility risks? This is the easiest pit to step on.
- Suggest providing the supplier with the specific model of the switch and requesting them to provide a compatibility test report.
- If your network device has encryption enabled, it is strongly recommended to purchase modules encoded by the original manufacturer, otherwise there is a risk of being unusable.
If you can provide specific connection distances, switch brands used, and existing fiber types, we can recommend the most suitable module solution for you.