Compounds. There are more carbon compounds than there are compounds of all other elements combined. The study of carbon compounds, both natural and synthetic, is called organic chemistry. Plastics, foods, textiles, and many other common substances contain carbon.
backplane is the shared capacity between interfaces on a switch switch fabric is also the shared capacity between interfaces on a switch and can also be the shared capacity between interfaces on multiple switches using some sort of interconnect, typically vendor specific.
Ethernet is the most widespread packet-based backhaul technology. While this service is a vast cost and scale improvement over TDM backhaul, carrier Ethernet is a stepping stone in the evolution of backhaul networks. Expect MNOs to move to true IP backhaul networks to meet the scalability needs of their expanding networks.