Hello Rehab,
I have some material that might help to understand these topics. First, I would make sure you become very familiar with VLANs and trunking. Go through unit 2 of the switching course:
Afterwards, read up on Metro Ethernet:
And try the Q-in-Q configuration example:
I don’t have anything on BDI but @lagapidis explained it a bit in this topic:
Good luck and if you have any questions, let us know ok?
Rene