100G QSFP28 Passive Direct Attach Copper Twinax (DAC)
Many enterprise switches and NICs can only use certified DAC/AOC and transceivers. Mostly they are very expensive. A good place to look for them is FS.com. They can provide cables for known brands like Cisco, Dell, HP, IBM, Juniper, Arista, Mellanox, and so on. They can even provide a custom-made cable, where, for instance, one side is Cisco and another side is Mellanox.
Because I bought a Mellanox NIC and have a Dell switch, I was unsure what cable to pick and whether I would like to change the Dell Switch operation system to Cumulus, for example. Do I need another cable? So, I contacted FS support, and after few minutes, I got an answer. They told me I needed a custom-made cable and write on device number “Dell to Mellanox”. Customer support was very friendly and helpful. The representative answered my questions very quickly and told me that the operating system wouldn’t affect this. Because I picked the Dual Combability Solution, I had to wait a little bit longer than usual.
My 100G QSFP28 DAC cables are 4-channel full-duplex, supporting a data rate of 25.78Gb/s (per channel). They are 2nd generation. Here is the datasheet (https://img-en.fs.com/file/datasheet/100g-qsfp28-passive-dac-twinax-cable.pdf)
If you want to read more about 100Gb Ethernet, then FS has published a nice blog post: https://community.fs.com/blog/100g-ethernet-is-gaining-broader-market.html
Cat6a Copper Trunk Cable
For better cable management, I bought Cat6A copper trunk cables. They are very good ones and make cable management simple. Soon I plan to buy more, but CAT6 copper trunk cables.
I would like to point out that FS service and support is really 5-star enterprise-class support. Even though I am a home labber who buys only small quantities, they are very friendly, helpful, and quick to answer my questions.