谁知道sdhl的线路怎么总是启不来

starter

我在两端的cisco 2620的串口上配了地址，用sdhl连接。
电信说线路正常，但我的路由不断显示以下信息：
07:38:38: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
07:38:58: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down
07:39:08: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
07:39:28: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down
07:39:38: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up
07:39:58: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down

各位看看是怎么回事？

谢谢

sr1461069

2端的配置贴出来