探讨cisco问题...

关于s1 is up ,line protocol is down 的问题？

两个路由分别通过各自的S1口连接

RA：A#sh int s1 Serial1 is up, line protocol is down Hardware is HD64570 Internet address is 10.1.0.1/24 MTU 1500 bytes, BW 64 Kbit, DLY 1000 usec, rely 255/255, load 1/255 Encapsulation HDLC, loopback not set, keepalive set (10 sec) Last input 00:00:00, output 00:00:00, output hang never Last clearing of show interface counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 1000 bits/sec, 2 packets/sec 5 minute output rate 1000 bits/sec, 2 packets/sec 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected 0 packets output, 0 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out

RB：

B#sh int s1 Serial1 is up, line protocol is down Hardware is HD64570 Internet address is 10.1.0.2/24 MTU 1500 bytes, BW 64 Kbit, DLY 1000 usec, rely 255/255, load 1/255 Encapsulation HDLC, loopback not set, keepalive set (10 sec) Last input 00:00:00, output 00:00:00, output hang never Last clearing of show interface counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops 5 minute input rate 1000 bits/sec, 2 packets/sec 5 minute output rate 1000 bits/sec, 2 packets/sec 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 0 input packets with dribble condition detected 0 packets output, 0 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out

RA ping 自己的S1 不通

RB ping 自己的S1 不通

如何解决！