cisco路由器常用的查看端口和通道状况的命令

cisco路由器常⽤的查看端⼝和通道状况的命令cisco, 路由器, 端⼝, 通道, 命令

下⾯以Cisco1800路由器为例，介绍⼀下常⽤的查看端⼝和通道状况的命令。在MS-DOS 窗⼝⾥敲⼊命令telnet+IP地址，回车，即可远程登录路由器。⼀般⽤路由器局域⽹⼝地址。

1，⽤R1#sh ip int b命令查看端⼝状态R1#sh ip int b

Interface IP-Address OK? Method Status ProtocolFastEthernet0/0 100.100.100.226 YES NVRAM up upFastEthernet0/1 200.200.200.226 YES NVRAM up upSerial0/0/0 72.22.81.102 YES NVRAM up upSerial0/0/1 72.22.81.109 YES NVRAM up up

正常情况下，思科1800路由器四个端⼝的Status和protocol都是up的。2，⽤R1#sh int s0/0/0查看链路状态和通道情况

Serial0/0/0 is up, line protocol is up //接⼝与协议都已启动（正常）

Serial0/0/0 is up, line protocol is down //接⼝启动，协议没有匹配成功（端⼝⽆物理故障，但通道不通）

Serial0/0/0 is down, line protocol is down （notconnect）//接⼝与协议都DOWN掉,本端端⼝没有与对⽅建⽴物理连接，可能是对⽅设备没有开启，对⽅端⼝故障或者线路故障造成。

Serial0/0/0 is down, line protocol is down //接⼝与协议都DOWN掉（协转没有⼯作）Serial0/0/0 is down,line protocol isdown（disable）//端⼝出现物理性故障，需更换端⼝。

Serial0/0/0 is administratively down,line protocol is down //接⼝关闭，可⽤命令打开。

Serial0/0/0 is up, line protocol is down（looped） //此通道上有环（⽆论在协转、DDF架、SDH上做环，在路由器⾥看到的显⽰是⼀样的）。

Serial0 is up, line protocol is downHardware is PowerQUICC Serial

Interface is unnumbered. Using address of FastEthernet0/0 (172.22.128.193) MTU 1500 bytes, BW 1544 Kbit, DLY 20000usec,

reliability 255/255, txload 1/255, rxload 1/255 //通道的可靠性Encapsulation PPP, LCP Listen, loopback not setLast input 00:00:27, output 00:00:27, output hang never

Last clearing of \"show interface\" counters 00:02:52 //上次计数器清零到现在的时

间

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing 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/sec5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec30 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// 输⼊错误包数量

60 packets output, 840 bytes, 0 underruns0 output errors, 0 collisions, 9 interface resets0 output buffer failures, 0 output buffers swapped out0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

通道的可靠性，正常值是255/255，如果低于254将会造成丢包。可靠性越低，通道越差，错误包越多。

DCD 数据载体检测DTE CARrfer derectDSR 数据设置就绪DATA SET READYDTR 数据终端就绪DTE IS READYRTS 请求发送Reguest To SendCTS 清除发送Clear To send3，路由器端⼝计数器清零

有故障的通道往往造成路由器接⼝的输⼊错误包数量很⾼，不便于⽐较查看。这时最好把接⼝数据包计数器清零，使其重新开始计数。⽤R1#clear coun命令清零。R1#clear coun4,判断以太⽹端⼝故障

⽤R1#sh int f0/0 来检查以太⽹⼝及其链路的状态，如下所⽰：R1#sh int f0/0

FastEthernet 0 is up,line protocol is up //连接正常Ethernet 0 is up,line protocol is down //连接故障，路由器没有连接到局域⽹Ethernet 0 is down,line protocol is down(disable) //接⼝故障

Ethernet 0 is administratively down,line protocol is down //接⼝被关闭，可⽤命令打开

5，查看相邻路由器

⽤R2#sh cdp nei命令查看相邻路由器，输出如下：R2#sh cdp nei

Capability Codes: R - Router, T - Trans Bridge, B - Source Route BridgeS - Switch, H - Host, I - IGMP, r - Repeater

Device ID Local Intrfce Holdtme Capability Platform Port IDR1 Ser 0/0/0 133 R S I 1841 Ser 0/0/1S2_SW1 Fas 0/0 125 S I WS-C2960-2Fas 0/6S2_SW2 Fas 0/1 140 S I WS-C2960-2Fas 0/22R3 Ser 0/0/1 156 R S I 1841 Ser 0/0/0

此命令可以查看到相邻的思科路由器和思科交换机，可以验证设备是否相通，以及连接关系是否正确。

6，观察路由器告警和报错信息

路由器发⽣故障或状态发⽣变化的时候，会发出告警、报错、提⽰信息。如果是⽤telnet 命令登录路由器的话，不能直接看到这些信息，需要输⼊R1# ter mon命令后，才能使这些信息显⽰在MS-DOS窗⼝上。R1#ter mon

该命令可以使你及时了解路由器状态变化，便于发现和排除故障。