Reason why MPO-12 qsfp28 transievers and cables exists
Greetings, so after a few years of working outside of network (I'm manly virtualization/server guy, but I was working with networks in 2019-2021) - my colleague recently asked me a question that left me stumbled.
The question is:
"We have 40/100G. Which is perfectly fine divided in 4 pairs, so 4 LC connectors and 8 lines. For what reason MPO-12 exists? In all cases where you connect any type of device (be it switch to switch, or switch to server) the 4 lines (2 pairs) remain unused. What the story behind 12core MPO transievers and 6LC connector?"
I googled around and only thing I was able to find "because legacy", but I don't remember such legacy, like there is no network standard that speed is divided by 6. At that point I'm already to take anecdotal reason "because 6 LC is more durable together, than 4", but it shouldn't be it, right?
Can somepne help me with this question?