cisco查看端口狀態命令

cisco查看端口狀態命令
在MS-DOS窗口裏敲入命令telnet+IP地址，回車，即可遠程登錄路由器。一般用路由器局域網口地址。
1，用R1#sh ip int b命令查看端口狀態
R1#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 100.100.100.226 YES NVRAM up up
FastEthernet0/1 200.200.200.226 YES NVRAM up up
Serial0/0/0 72.22.81.102 YES NVRAM up up
Serial0/0/1 72.22.81.109 YES NVRAM up up
正常情況下，思科1800路由器四個端口的Status和protocol都是up的。

2，用R1#sh int s0/0/0查看鏈路狀態和通道情況
Serial0/0/0 is up, line protocol is up //接口與協議都已啟動（正常）
Serial0/0/0 is up, line protocol is down //接口啟動，協議沒有匹配成功（端口無物理故障，但通道不通）
Serial0/0/0 is down, line protocol is down //接口與協議都DOWN掉（協轉沒有工作）
Serial0/0/0 is down,line protocol is down（disable）//端口出現物理性故障，需更換端口。
Serial0/0/0 is administratively down,line protocol is down //接口關閉，可用命令打開。
Serial0/0/0 is up, line protocol is down（looped） //此通道上有環（無論在協轉、DDF架、SDH上做環，在路由器裏看到的顯示是一樣的）。

Serial0 is up, line protocol is down
Hardware is PowerQUICC Serial
Interface is unnumbered. Using address of FastEthernet0/0 (172.22.128.193)
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255 //通道的可靠性
Encapsulation PPP, LCP Listen, loopback not set
Last input 00:00:27, output 00:00:27, output hang never
Last clearing of "show interface" counters 00:02:52 //上次計數器清零到現在的時間
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/2/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 1158 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
30 packets input, 420 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
6552 input errors, 0 CRC, 4 frame, 0 overrun, 0 ignored, 0 abort// 輸入錯誤包數量
60 packets output, 840 bytes, 0 underruns
0 output errors, 0 collisions, 9 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
通道的可靠性，正常值是255/255，如果低於254將會造成丟包。可靠性越低，通道越差，錯誤包越多。

DCD 數據載體檢測DTE CARrfer derect
DSR 數據設置就緒DATA SET READY
DTR 數據終端就緒DTE IS READY
RTS 請求發送Reguest To Send
CTS 清除發送Clear To send

3，路由器端口計數器清零
有故障的通道往往造成路由器接口的輸入錯誤包數量很高，不便於比較查看。這時最好把接口數據包計數器清零，使其重新開始計數。用R1#clear coun命令清零。
R1#clear coun

4,判斷以太網端口故障
用R1#sh int f0/0 來檢查以太網口及其鏈路的狀態，如下所示：
R1#sh int f0/0
FastEthernet 0 is up,line protocol is up //連接正常
Ethernet 0 is up,line protocol is down //連接故障，路由器沒有連接到局域網
Ethernet 0 is down,line protocol is down(disable) //接口故障
Ethernet 0 is administratively down,line protocol is down //接口被關閉，可用命令打開

5，查看相鄰路由器
用R2#sh cdp nei命令查看相鄰路由器，輸出如下：
R2#sh cdp nei
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater

Device ID Local Intrfce Holdtme Capability Platform Port ID
R1 Ser 0/0/0 133 R S I 1841 Ser 0/0/1
S2_SW1 Fas 0/0 125 S I WS-C2960-2Fas 0/6
S2_SW2 Fas 0/1 140 S I WS-C2960-2Fas 0/22
R3 Ser 0/0/1 156 R S I 1841 Ser 0/0/0
此命令可以查看到相鄰的思科路由器和思科交換機，可以驗證設備是否相通，以及連接關係是否正確。

6，觀察路由器告警和報錯信息
路由器發生故障或狀態發生變化的時候，會發出告警、報錯、提示信息。如果是用telnet命令登錄路由器的話，不能直接看到這些信息，需要輸入R1# ter mon命令後，才能使這些信息顯示在MS-DOS窗口上。
R1#ter mon
該命令可以使你及時了解路由器狀態變化，便於發現和排除故障。