What are the Pros and Cons of Using OSFPs or QSFP-DDs?
Optical transceivers such as OSFP (Octal Small Form Factor Pluggable) and QSFP-DD (Quad Small Form Factor Pluggable Double Density) are integral to significant high-speed, high-density networking applications in data centers and telecommunications. Dealing with new network speeds and managing bandwidth needs, different factors might lead to a preference for one over the other.
Before listing the pros and cons, it is important to note the crucial differences between them:
1. Form Factor: OSFP is larger than QSFP-DD, resulting in a lower port density. However, this larger size allows OSFP to handle higher wattage, providing better heat dissipation and therefore potentially higher bandwidth per port in the future.
2. Compatibility: QSFP-DD was designed with backward compatibility with QSFP28 in mind. You can use existing QSFP28 cables and modules in a QSFP-DD port.
Now, let’t discuss some of the pros and cons:
OSFP
Pros:
1. Higher Power Handling: OSFP can handle higher power up to 15W, accommodating future bandwidth needs. There is the potential to reach up to 800Gbps for future uses.
2. Thermal Efficiency: The larger form factor leads to better heat dissipation, which may become increasingly important as connections’ power utilization and density increase.
Cons:
1. Low Port Density: Due to their larger size, data center rack units fitted with OSFP ports have a lower overall port density compared to those using QSFP-DD.
2. No Backward Compatibility: OSFP is not backward compatible with existing form factors, which can complicate upgrades and increase costs.
QSFP-DD
Pros:
1. Backward Compatibility: QSFP-DD is backward compatible with QSFP, and QSFP28 modules. This allows for easier upgrading while lowering costs by reusing existing hardware.
2. High Port Density: The smaller QSFP-DD form factor allows for more ports on a single switch, leading to a more compact and dense arrangement which can save precious space in data centers.
Cons:
1. Lower Power Handling: QSFP-DD power handling is lower than OSFP, making it harder to scale for future increased transmission rates.
2. Thermal Concerns: Due to the high port density and higher power demand for future standards, managing thermal dissipation may become a challenge.
The choice between QSFP-DD and OSFP will depend on your specific circumstances and long-term network goals. If you have existing QSFP infrastructure and you’re seeking a high-density configuration with measured growth in mind, QSFP-DD is a solid choice. If, however, you’re preparing for immense growth and want to set up your data center for future advancements (especially those requiring high power and efficient thermal handling), OSFP could be the better choice.
FAQS
Q: 400G QSFP-DD vs 400G OSFP/CFP8: What are the differences?
A: The table below includes detailed comparisons for the three main form factors of 400G transceivers.
| 400G Transceiver | 400G QSFP-DD | 400G OSFP | CFP8 |
|---|---|---|---|
| Application Scenario | Data center | Data center & telecom | Telecom |
| Size | 18.35mm× 89.4mm× 8.5mm | 22.58mm× 107.8mm× 13mm | 40mm× 102mm× 9.5mm |
| Max Power Consumption | 12W | 15W | 24W |
| Backward Compatibility with QSFP28 | Yes | Through adapter | No |
| Electrical signaling (Gbps) | 8× 50G | ||
| Switch Port Density (1RU) | 36 | 36 | 16 |
| Media Type | MMF & SMF | ||
| Hot Pluggable | Yes | ||
| Thermal Management | Indirect | Direct | Indirect |
| Support 800G | No | Yes | No |
Q: How does the QSFP+ to SFP+ fiber convertor allow 4x 10G?
A: To enable 4x 10G connectivity, a QSFP+ to SFP+ fiber converter utilizes a breakout cable. This cable splits the 40G channel provided by the QSFP+ transceiver into four individual 10G channels, each connected to an SFP+ transceiver. Essentially, the converter breaks down the high-speed 40G signal into four separate 10G signals, allowing each SFP+ port to transmit data at 10G speeds. This configuration is beneficial for scenarios where equipment with SFP+ interfaces needs to communicate with a device equipped with a QSFP+ port, providing flexibility and compatibility in networking setups.
Q: What does “SR8”, “DR4”, “XDR4”, “FR4”, and “LR4” mean?
A: “SR” refers to short range, and “8” implies there are 8 optical channels. “DR” refers to 500m reach using single-mode fiber, and “4” implies there are 4 optical channels. “XDR4” is short for “eXtended reach DR4”. And “LR” refers to 10km reach using single-mode fiber.
Q: Can I plug an OSFP transceiver module into a QSFP-DD port?
A: No. QSFP-DD and OSFP are totally different form factors. For more information about QSFP-DD transceivers, you can refer to 400G QSFP-DD Transceiver Types Overview. You can use only one kind of form factor in the corresponding system. E.g., if you have an OSFP system, OSFP transceivers and cables must be used.
Q: What other breakout options are possible apart from using OSFP modules mentioned above?
A: OSFP 400G DACs & AOCs are possible for breakout 400G connections. See 400G Direct Attach Cables (DAC & AOC) Overview for more information about 400G DACs & AOCs.
Q1: What is the difference between QSFP28 ER4 and QSFP28 ER4 Lite Module?
A: The QSFP 100G ER4 has a series of BER requirements of better than 1E-12 without FEC optical modules. However, the receiving sensitivity of 100G QSFP28 ER4 is not satisfied with the existing APD technology. Therefore, many optical module manufacturers/suppliers defined a non-standard 100Gbase ER4 Lite module with a QSFP28 package where the largest transmission distance is up to 40km with FEC or 30km without FEC.?Walsun provides the QSFP28 100G ER4 Lite module compliant with the Ethernet 100Gbase ER4 Lite standard to meet the harshest external operating conditions including temperature, humidity, and EMI interference.
Q2: How does the QSFP 100G ER4 Module differ from the QSFP28 4WDM?
A: The QSFP 100G ER4 optical transceiver supports dual 100G Ethernet applications while the 100G QSFP28 4DWM only supports 100G Ethernet applications. The commons and differences are listed below.
| Form Type | QSFP28 ER4 | QSFP28 4WDM | ||
|---|---|---|---|---|
| Max Data Rate | 25.78125Gbps/27.95Gbps | 25.78125Gbps | ||
| Max Cable Distance | 40km | 10km | 20km | 40km |
| Center Wavelength | 1295.56nm, 1300.05nm, 1304.58nm, 1309.14nm | 1271nm, 1291nm, 1311nm, 1331nm | 1295.56nm, 1300.05nm, 1304.58nm, 1309.14nm | 1295.56nm, 1300.05nm, 1304.58nm, 1309.14nm |
| FEC Requirement | Without FEC (BER 1E-12) | With FEC (BER 5E-5) | ||
| Receiver | SOA+PIN ROSA | PIN ROSA | PIN ROSA | APD ROSA |
| Cooling Requirement | Cooled | Uncooled | Cooled | Cooled |
