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Solving a Thermal Challenge

Posted by Frank Yang on Nov 5, 2021

A 100G Active Optical Cable in a data center

The optical communications market remained strong in the second quarter of 2021. Approved Networks (a branch of Legrand) has also seen strong growth across optics, Direct Attach Cables (DACs), and especially Active Optical Cables (AOCs). One of the reasons for the exponential growth of the 100G server is networking connectivity.

In some cases, a large data center operator may have a thermal issue that needs to be addressed. To fix this problem for their customers, engineers may need to connect the Top of Rack (ToR) switch to the rack servers with an installed 100 Gigabit Ethernet (GbE) Network Interface Card (NIC).

An optical connectivity solution rated for up to 850 C may be required. With a 1 Rack Unit (1RU) server fully populated with hard drives and equipped with either dual high-performance gold (or platinum) processors, a dual-port 100 GbE NIC should be used. The placement of the major server components is illustrated in the figure below. As you may notice, the cooling airflow around the NIC cards is not ideal due to the blockage of the hard drives and the narrow space inside the chassis. Essentially, the environment inside the server chassis is causing the thermal issue.

Our engineers ruled out the option of not fully populating the hard drives, which might have improved airflow inside the chassis. The server inlet temperature and the cooling airflow volume may also be out of your control.

But what would be the optical connectivity solution for this thermal challenge?

Diagram showing the thermal challenge with hard drives, cooling fans, processors and PCI-E slot

Besides the thermal challenge, the complexity of the network design may also be an issue. A ToR switch that is made by Juniper, and a NIC that is made by Mellanox both require specific vendor codes in the EEPROM of optical connectivity products for compatibility. So, what would be a cost-effective optical connectivity solution for connecting the network equipment made by different manufacturers?

Our engineers may be able to help you with this multi-vendor 100G QSFP28 AOC specified for the industrial temperature range. The AOC meets the 850 C thermal requirement and also guarantees the compatibility of the Juniper switch with the Mellanox 100 GbE NIC.