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永久虚电路(PVC:Permanent Virtual Circuit)它是端点和业务类别由网络管理定义的帧中继逻辑链路.与X.25永久虚电路相类似,PVC由始发帧中继网络元素地址、始发数据链路控制标识、终接帧中继网络元素地址和终接数据链路控制标识组成.始发是指启动PVC的接入接口,终接是指PVC终止的接入接口.许多数据网络客户需要两个端点之间的PVC.有连续通信需求的数据终端设备使用PVC.交换虚电路(SVC:Switched Virtual Circuit)它是在公用通信网络中任意两节点间每次传输时建立和拆除的逻辑链路.由于路由器或帧中继接入设备(FRAD)中只需把地址编入程序,所以SVC简化了配置.SVC永远是双工的.
PVC: Permanent Virtual Circuit It is a frame relay logical link whose endpoint and service class are defined by network management. Similar to the X.25 permanent virtual circuit, the PVC consists of the address of the originating frame relay network element, The data link control identity, the address of the terminating frame relay network element, and the terminating data link control identity, originating means starting the PVC access interface, terminating means the PVC terminating access interface, and many data networks Customers need PVCs between two endpoints Data terminal devices that need continuous communication use PVC PVCs: Switched Virtual Circuit It is a network that is established and removed on every transmission between any two nodes in a public communication network Logical Links SVC simplifies the configuration because only the address needs to be programmed into the router or Frame Relay Access Device (FRAD), which is always duplex.