大家帮个忙啊，关于CISCO2511的一个设置...

Router#show int s0 Hardware is HD64570 Internet address is 10.0.0.5/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation PPP, loopback not set, keepalive set (10 sec) LCP Closed Closed: IPCP, CDPCP Last input 00:00:01, output 00:00:53, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 3988 packets input, 176238 bytes, 0 no buffer Received 4 broadcasts, 0 runts, 0 giants, 0 throttles 4 input errors, 4 CRC, 2 frame, 0 overrun, 0 ignored, 0 abort 2905 packets output, 139818 bytes, 0 underruns 0 output errors, 0 collisions, 128 interface resets 0 output buffer failures, 0 output buffers swapped out 6 carrier transitions DCD=down DSR=down DTR=up RTS=up CTS=down

为什么S0端口的IP和协议都起不来？

网络拓朴是这样的：

两台E1/V35的协议转换器，背对背连，两台ROUTE接两边，

把CISCO 的ROUTE与其中一台E1/V35连接是没有问题的，如下：

Serial0 is up, line protocol is up Hardware is HD64570 Internet address is 10.0.0.5/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255 Encapsulation PPP, loopback not set, keepalive set (10 sec) LCP Open Listen: CDPCP Open: IPCP Last input 00:00:00, output 00:00:00, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0 (size/max/drops); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 179 packets input, 3704 bytes, 0 no buffer Received 4 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 119 packets output, 1549 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 output buffer failures, 0 output buffers swapped out 1 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up

而与另一台E1/V35连接就出现最上面那种情况，

知情人可否告知下啊？

谢谢