1.6T OSFP<\/strong>: 25-33W per module (projected)<\/li>\n<\/ul>\n\n\n\nThe thermal load between two points in the system causes network performance impacts that can be observed. The failure rate of electronic components increases by approximately double when the operating temperature rises by 10\u00b0C. Bit error rates increase for modules operating at 70\u00b0C compared to modules that run at 50\u00b0C. Equipment thermal management requires two functions, which include protecting equipment from breakdowns and achieving peak efficiency throughout its operational lifespan.<\/p>\n\n\n\n
The OSFP form factor provides built-in thermal benefits. The OSFP modules, which have 30% greater surface area than QSFP-DD, achieve better heat dissipation performance. The system’s design enables heat sinks to be installed while establishing optimal thermal contact with switch cages. The design choice of OSFP power handling capacity increases with speed improvements.<\/p>\n\n\n\n<\/span>OSFP-IHS (Integrated Heat Sink)<\/strong><\/strong><\/span><\/h3>\n\n\n\nThe OSFP-IHS modules feature thermal management systems that operate without external assistance in air-cooled systems. The IHS designation stands for Integrated Heat Sink, indicating the module includes its own heat dissipation mechanism rather than relying entirely on the host system.<\/p>\n\n\n\n
Design Characteristics<\/strong><\/p>\n\n\n\nIHS modules measure 13mm in height, including the integrated heat sink structure. The thermal design uses one of three configurations:<\/p>\n\n\n\n
\nOpen finned-top<\/strong>: Exposed metal fins maximize surface area for convective cooling. Air flows directly across the fins, carrying heat away from the module. This design provides the best thermal performance for air-cooled environments.<\/li>\n\n\n\nClosed finned-top<\/strong>: Partially enclosed fins balance cooling performance with mechanical protection and electromagnetic interference shielding. The enclosure prevents physical damage to delicate fins while maintaining adequate airflow.<\/li>\n\n\n\nFlat-top<\/strong>: A simple metal casing without external fins relies on chassis airflow and conduction through the module base. Suitable for moderate power applications in well-designed cooling environments.<\/li>\n<\/ul>\n\n\n\nThermal Performance<\/strong><\/p>\n\n\n\nThe IHS modules manage a power range between 16 watts and 18 watts when they use standard grey optics, which include SR8, DR8, and FR8. The extended-power versions of the system enable users to operate coherent optics ZR and ZR plus at power levels exceeding 20 watts because they provide additional thermal capacity. The IHS modules use their self-contained design to work with standard OSFP cages, which exist in Arista, Cisco, Juniper, and other major switch vendor products.<\/p>\n\n\n\n
The system uses forced convection as its cooling mechanism because switch fans create airflow that moves through the chassis and across module heat sinks and finally exits through the exhaust. Thermal efficiency depends on airflow velocity, intake air temperature, and the thermal resistance of the heat sink design.<\/p>\n\n\n\n<\/span>OSFP-RHS (Riding Heat Sink)<\/strong><\/strong><\/span><\/h3>\n\n\n\nOSFP-RHS modules take a different approach to thermal management. The RHS designation stands for Riding Heat Sink, which describes the module’s design that operates on its own thermal management system because it connects with the host system’s heat dissipation system.<\/p>\n\n\n\n
Design Characteristics<\/strong><\/p>\n\n\n\nRHS modules feature a flat metal top surface that reaches a height of 9.5mm, which is lower than IHS variants. The flat surface makes contact with a thermal interface material (TIM), which transfers heat to the cooling solution that the host system provides. The design eliminates the integrated heat sink, relying instead on system-level thermal management.<\/p>\n\n\n\n
RHS modules require specific cages designed for this thermal interface. The cages include different positive stops to prevent accidental insertion of RHS modules into standard IHS cages, which would result in inadequate cooling and potential thermal damage.<\/p>\n\n\n\n
Thermal Performance<\/strong><\/p>\n\n\n\nThe design of the RHS system provides improved heat transfer performance to its advanced cooling systems. The RHS modules achieve power handling capabilities that match IHS variants through their direct connection to cold plates and centralized heat sinks. The system-level approach of the system distributes thermal load across multiple surface areas, while it allows for liquid cooling systems to be integrated.<\/p>\n\n\n\n
RHS modules are particularly common in network interface cards (NICs) and data processing units (DPUs) because space limitations and shared thermal systems make it impossible to use integrated heat sinks. The design of the system includes a flat profile, which enables certain configurations to achieve greater port density.<\/p>\n\n\n\n
<\/span>IHS vs RHS Thermal Comparison<\/strong><\/strong><\/span><\/h3>\n\n\n\nFeature<\/strong><\/strong><\/td>OSFP-IHS<\/strong><\/strong><\/td>OSFP-RHS<\/strong><\/strong><\/td><\/tr>Height<\/strong><\/td>13mm<\/td> 9.5mm<\/td><\/tr> Cooling Method<\/strong><\/td>Module-level air cooling<\/td> System-level conductive cooling<\/td><\/tr> Primary Medium<\/strong><\/td>Forced air convection<\/td> Liquid cold plates or centralized heat sinks<\/td><\/tr> Max Power<\/strong><\/td>20W+<\/td> 20W+ (better efficiency at high power)<\/td><\/tr> Port Density<\/strong><\/td>Lower (taller profile)<\/td> Higher (compact design)<\/td><\/tr> Deployment Flexibility<\/strong><\/td>High (any compatible host with airflow)<\/td> Low (requires specific thermal infrastructure)<\/td><\/tr> Cage Requirement<\/strong><\/td>Standard OSFP cages<\/td> RHS-specific cages<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nSelection Guidance<\/strong>: The IHS system serves traditional air-cooled data centers, which use standard switch infrastructure. The RHS system should be chosen for liquid-cooled facilities and high-density AI clusters and NIC\/DPU deployments that need system-level thermal control. The two systems, IHS and RHS, should never be combined because their different thermal properties lead to overheating issues in the same cage type.<\/p>\n\n\n\n<\/span>OSFP Power Consumption Reality<\/strong><\/strong><\/span><\/h2>\n\n\n\n<\/span>Real-World Power Consumption by Module Type<\/strong><\/strong><\/span><\/h3>\n\n\n\nDatasheet specifications provide typical power consumption under reference conditions. Actual power consumption in real-world applications exceeds standard levels because of temperature changes, signal processing needs, and differences in manufacturing processes.<\/p>\n\n\n\nModule Type<\/strong><\/strong><\/td>Datasheet Typical<\/strong><\/strong><\/td>Real-World Range<\/strong><\/strong><\/td>Notes<\/strong><\/strong><\/td><\/tr>400G SR8<\/a><\/td> 12W<\/td> 12-15W<\/td> Short reach, lower power<\/td><\/tr> 400G DR8<\/td> 15W<\/td> 15-18W<\/td> Common data center interconnect<\/td><\/tr> 800G SR8<\/a><\/td> 14W<\/td> 14-17W<\/td> Multimode, moderate power<\/td><\/tr> 800G DR8<\/a><\/td> 18W<\/td> 16-20W<\/td> Single-mode, higher DSP load<\/td><\/tr> 800G FR8<\/td> 18W<\/td> 17-21W<\/td> Extended reach optics<\/td><\/tr> 800G ZR\/ZR+<\/td> 20W<\/td> 20-25W<\/td> Coherent optics, highest power<\/td><\/tr> 1.6T DR8<\/a><\/td> 25W<\/td> 25-33W<\/td> Next-generation modules<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nThe thermal planning process requires assessment of both standard power levels and maximum power requirements. A module specified at 18W typical might consume 20W under heavy load in a warm environment. The system requires more thermal capacity, which results from planning all fire incidents.<\/p>\n\n\n\n
The Linear Pluggable Optics LPO modules achieve power reductions because they remove the Digital Signal Processing DSP component. LPO variants consume 7-8.5W compared to 14-17W for standard DSP-based modules. The LPO modules enable optics power reduction up to 50%, but this comes with limitations in operational distance and available functions when rack thermal capacity is restricted.<\/p>\n\n\n\n
<\/span>Switch-Level Power Calculations<\/strong><\/strong><\/span><\/h3>\n\n\n\nUnderstanding module power is only half the thermal equation. The complete thermal load includes switch silicon, optical modules, and system overhead.<\/p>\n\n\n\n
Example: 32-Port 800G Switch<\/strong><\/p>\n\n\n\nComponent<\/strong><\/strong><\/td>Calculation<\/strong><\/strong><\/td>Power<\/strong><\/strong><\/td><\/tr>Switch ASIC\/Silicon<\/td> Modern 51.2T switch<\/td> ~450W<\/td><\/tr> 800G OSFP Optics<\/td> 32 ports \u00d7 18W average<\/td> 576W<\/td><\/tr> System Overhead<\/td> Fans, power supply loss, control plane<\/td> ~75W<\/td><\/tr> Total<\/strong><\/td> <\/td> ~1,101W<\/strong><\/td><\/tr>Heat Output<\/strong><\/td>1,101W \u00d7 3.41 BTU\/hr\/W<\/td> 3,754 BTU\/hr<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\nThe analysis reveals that optical modules in this configuration account for 52 percent of total power usage by switches. The transceivers, not the switch silicon, dominate the thermal budget. The pattern that exists here represents standard behavior for high-density 800G deployments and shows the necessity of optical thermal planning.<\/p>\n\n\n\nFor a 64-port 800G switch, the thermal load doubles:<\/p>\n\n\n\n
\nOptics: 1,152W (64 \u00d7 18W)<\/li>\n\n\n\n ASIC: ~500W<\/li>\n\n\n\n Overhead: ~100W<\/li>\n\n\n\n Total: ~1,752W (5,974 BTU\/hr)<\/strong><\/li>\n<\/ul>\n\n\n\n<\/span>Power Trends Impact<\/strong><\/strong><\/span><\/h3>\n\n\n\nThe transition from 400G to 800G to 1.6T creates thermal load increases that match the capacity of the system. Each speed generation approximately doubles the power per bit while doubling the bits per port. The net result shows that each generation brings a power increase between 2 times and 2.5 times for every port.<\/p>\n\n\n\n
Thermal Planning Implications<\/strong>:<\/p>\n\n\n\n\n400G to 800G migration<\/strong>: Expect 1.5-2x increase in rack thermal load<\/li>\n\n\n\n800G to 1.6T migration<\/strong>: Expect 1.5-2x additional increase<\/li>\n\n\n\nInfrastructure lifecycle<\/strong>: Cooling designed for 400G may be inadequate for 800G, and certainly insufficient for 1.6T<\/li>\n<\/ul>\n\n\n\n