Cisco路由器故障判斷及排除

　　明白show line輸出的含義

　　Show line line-number EXEC是非常有用的trobbleshooting命令.

　　現(xiàn)象:MODEM和路由器間無連接.試用反登錄無反應(yīng)或用戶收到"Connection Refused by Foreign Host"信息.

　　建議:

　　用show line看MODEM一欄是否是"inout",若不是,在路由器上:

　　Router#conf t

　　Router(config)#line aux 0

　　Router(config-line)#modem inout

　　Router(config-line)#^Z

　　Router#

　　確定正確的線纜.

　　硬件問題,請(qǐng)與你的代理聯(lián)系.

　　現(xiàn)象:MODEM不撥號(hào).

　　建議:MODEM不撥號(hào),排除掉硬件,線纜的可能,就是:

　　不感興趣的包.用show running-config檢查路由器配置,是否設(shè)置了dialer-list截段了你想傳送的包,若是請(qǐng)重新配置access-list表.

　　Chat script配置錯(cuò)誤.打開debug信息.

　　Router#debug dialer

　　%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to down

　　%LINK-3-UPDOWN: Interface Serial0, changed state to down

　　%LINK-3-UPDOWN: Interface Async1, changed state to down

　　Async1: re-enable timeout

　　Async1: sending broadcast to default destination get_free_dialer: faking it

　　Async1: Dialing cause: Async1: ip PERMIT

　　Async1:No holdq created - not configured

　　Async1: Attempting to dial 8292

　　CHAT1: Attempting async line dialer script

　　CHAT1: Dialing using Modem script: backup & System script: none -- failed, not connected

　　CHAT1: process started

　　CHAT1: Asserting DTR

　　CHAT1: Chat script backup started

　　CHAT1: Expecting string:

　　Async1: sending broadcast to default destination -- failed, not connected

　　CHAT1: Timeout expecting:

　　CHAT1: Chat script backup finished, status = Connection timed out; remote host not responding

　　Async1: disconnecting call

　　......

　　------------------------------------------------------------

　　幀中繼連接的Troubleshooting

　　用show interface serial查看interface和line protocol是否up.確定連接的線纜正確.

　　如果interface is up,但line protocol是down.用show frame-relay lmi查看幀中繼的LMI類型.

　　用show frame-relay map查看打包類型.

　　用show frame-relay pvc查看PVC.

　　打開debug信息.

　　------------------------------------------------------------

　　X.25連接的Troubleshooting

　　確定兩個(gè)X.25端口連接上.

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