The sender removes the message from the ring. Metropolitan Area Networks ATM LAN uses a Star, usually with fiber optics running at 155Mbps. An electronic switch provides the connections. ATM is a connection-oriented network that does not use shared media. Distributed Queue Dual Bus uses a pair of fiber buses.
Nodes send a request for a cell to upstream nodes.
The upstream nodes allow an empty cell to pass by for each request received. Star - All stations are connected to a central switch. Ring - The computers are connected in a circle. Each computer sends data only to its left neighbor and receives data only from its right neighbor. Bus - All stations connect to a single wire, usually a coax cable.