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The cabling method for 200G networks primarily depends on the packaging form of the 200G transceivers (QSFP56 or QSFP-DD) and the signal modulation scheme (PAM4).
Currently, the mainstream 200G cabling solutions are primarily categorized into the following 4 TYPES:
Multi mode short-range cabling (SR4) – mainstream solution
This is the most common 200G solution within data centers, suitable for connecting cabinets within 100 meters.
- Ethernet optical transceiver: 200G QSFP56 SR4.
- Cable: MPO-12 (Base-8) multimode fiber optic patch cord (OM3/OM4/OM5).
- Principle: Adopting 4-channel parallel transmission, with 50G PAM4 per channel. Use 8-core optical fiber (4 transmitter and 4 receiver).
- Characteristics: 200GBASE SR4 is relatively low cost, widely used for switch stacking.
Single mode parallel cabling (DR4/PSM4) – medium to short distance
Suitable for single-mode fiber environments within 500 meters.
- Ethernet optical transceiver: 200G QSFP56 DR4
- Cable: MPO-12 (APC) single mode patch cord (yellow / green connector).
- Principle: It is also 4-channel parallel, with 50G PAM4 per channel. Use 8-core optical fiber (4 transmitter and 4 receiver).
- Features: 200GBASE DR4 is suitable for breaking out two 200G ports from a 400G DR4 port
Single mode dual core long-distance cabling (FR4/LR4) – saving fiber
Suitable for connections between 2 kilometers (FR4) and 10 kilometers (LR4).
- Ethernet optical transceiver: 200G QSFP56 FR4 or LR4
- Cable: Duplex LC single mode fiber patch cable
- Principle: Using CWDM (coarse wavelength division multiplexing) technology, four 50G signals are combined into a pair of optical fibers.
- Features: 200GBASE FR4 / LR4 only need one pair of optical fibers (2 cores), greatly saving the cost of long-distance wiring.
SFP direct attach cable and active optical cable assembly (DAC/AOC) – extremely short distance
Used for direct connection of equipment within the same cabinet (within 3 meters) or adjacent cabinets (within 30 meters).
- Product: 200G QSFP56 DAC Cable (copper wire) or 200G QSFP56 AOC Cable (optoelectronic integrated).
- Features: No need to purchase additional modules, plug and play, lowest power consumption, making AOC cable DAC cable the preferred choice for server access switches.
Conclusion
After the above explanation, I believe you have a general understanding of the four wiring methods for 200G and the fiber optic products they will use. Yingda use a table to compare them more intuitively as below:
| Solution Type | Part no. | Optical Interface | Recommend cable type | Max. Transmission distance |
| Multi mode parallel | SR4 | MPO-12 (PC) | OM4 (aqua / purple) | 100m |
| Single mode parallel | DR4 | MPO-12 (APC) | OS2 (yellow) | 500m |
| Single mode dual core | FR4 / LR4 | Duplex LC | OS2 (yellow) | 2km / 10km |
| Short distance direct connection | DAC / AOC | Integrated packaging | Pre made with cables | 3m / 30m |
KIND NOTES:
- Package matching: Ensure that both devices support QSFP56 (a package specifically optimized for 200G). Some early 200G transceiver were packaged in QSFP-DD (usually used for 400G), which have the same physical size but different electrical characteristics and cannot be mixed.
- APC vs UPC: As long as it is a single-mode MPO (such as DR4), an MPO 12 APC (green) connector must be used. If it is multimode MPO (such as SR4), please use MPO 12 UPC (aqua) connector is ok.