Hi I wish to learn more about NICs. And I would really appreciate any answers or resources you could point me to! We have a small cluster at work, and I'm thinking about getting 2 to learn with at home.
1) On our 10G network at work, would a 40G NIC make any difference? I read online 40G means 4x10G, and this makes me think it's not "true" 40G?
2) What are the dual-port NICs used for? Could using only 1 of the 2 ports lead to better performance than using both? Does a dual port 40G card mean 80G, provided your switch is set to handle that.
3) I have 2 Linux desktops at home, and I want to install my own driver, and try some tests. I will put in 1 NIC per desktop. I don't have a switch or router. Would a single QSFP+ to QSFP+ cable be able to directly connect these 2 computers for UDP/TCP traffic? I read about crossover cables, but these appear to be copper-only.
4) Is copper "slower" (assuming < 5 feet distance) than optical? I want to mention we use InfiniBand/RDMA at work and so I'm trying to measure performance on scale of nanos, so if copper is slower by >100ns then this is not feasible for my tests.
Thinking about the Chelsio T5 series, and using their provided userspace driver.
Thank you so much!
Edit: if this helps with how you want to structure your answer--I have had elementary exposure to networking and hardware at work, but I am a full time programmer. I have not experimented with device drivers, hence my interest in this area.