路由器做chap认证，出现Serial0/1 is up, line protocol is down

检查了chap的配置，检查了IP和子网掩码，DCE端也配置了时钟频率，但是一直是这样
Serial0/1 is up, line protocol is down
Mode=Sync DCE Speed=64000

Serial0/2 is up, line protocol is down
Mode=Sync DTE