In BUS topology every computer is directly connected to primary network cable in a single way. Bus networks are the easiest way to connect multiple users, but can have problems when two users want to transfer at the same time on the similar bus. Thus machines which need bus network architectures usually have some scheme of collision avoidance or collision handling for communication on the bus, quite usually using Carrier Sense Multiple Access or the attendance of a bus master which operates access to the shared bus source.