一台路由器接口信息显示如下 Serial0/0 current state: UP Line protocol current state: DOWN Physical layer is synchronous, Baudrate is 64000 bps Interface is DCE, Cable type is V、35, Clock mode is DCECLK 那么该接口上可能封装或运行了哪种协议 。
A.PPP
B.HDLC
C.Frame Relay
D.RIP
E.以上答案都不正确
正确答案是ABCD