单项选择题
【案例分析题】
Frame Relay is simplified form of () ,similar in principle to () , in which synchronous, frames of data are routed to different destinations depending on header information. Packets are routed throught one or more Virtual Circuits known as () . Most Virtual Circuits are () ,which means that the network provider sets up all DLCI connections at subscription time. () are also part of the Frame Relay specification. They privide a link that only lasts only as long as the session.
Most Virtual Circuits are () ,which means that the network provider sets up all DLCI connections at subscription time.