Re: I have windows 2012R2 OS on Dell R710.When i connect mellanox nics and cables through a Dell switch with 40G ports, It shows network cable unplugged.

He is saying Dell switch, I don't think that it is InfiniBand.

Few questions:

Did you install WinOF driver?

Could you make sure that the port is configured with Ethernet (if this is the case)?

Try to replace cable or switch port to make sure that there is no problem with the HW.

Thanks,

Ophir.