Cisco CCNA / CCNP Certification Exam: Troubleshooting Immediate Serial Connections
A major matter within your CCNA and CCNP CIT tests might be connecting Cisco routers specifically by means of their Serial interfaces, and though the configuration is simple, there are many very important particulars and present commands you will need to know so as to pass the exams and configure this effectively in output and residential lab networks. Enable’s Have a look at a sample configuration.
Connecting Cisco routers directly by means of their Serial interfaces performs very well once you get it jogging – and having this kind of relationship up and operating is simple plenty of. You should use show controller serial x to determine which endpoint is acting as the DCE, and it’s the DCE that need to be configured While using the clockrate command.
R3#show controller serial one
HD device 1, idb = 0x11B4DC, driver construction at 0x121868
buffer sizing 1524 High definition unit one, V.35 DCE cable
R3(config)#int serial1
R3(config-if)#ip deal with 172.12.13.3 255.255.255.0
R3(config-if)#clockrate 56000
R3(config-if)#no shut
Failure to configure the clockrate has some intriguing consequences regarding the physical and rational point out from the interfaces. Permit’s clear away the clockrate from R3 and find out what comes about.
R3(config)#int s1
R3(config-if)#no clockrate 56000
R3(config-if)#
18:02:19: %LINEPROTO-five-UPDOWN: Line protocol on Interface Serial1, transformed condition to down
The road protocol doesn’t fall immediately, but it does fall. Enable’s operate exhibit interface serial1 to match the Bodily and sensible interface states.
R3#display int 메이저사이트 serial1
Serial1 is up, line protocol is down
Bodily, the interface is okay, so the Bodily interface is up. It’s http://www.bbc.co.uk/search?q=토토사이트 just the sensible Section of the interface – the road protocol – that's down. It’s exactly the same scenario on R1.
R1#exhibit inter serial1
While a router misconfiguration would be the almost certainly explanation for a serial link issue, that’s not the only real cause for clocking problems. Cisco’s website documentation mentions CSU/DSU misconfiguration, out-of-spec cables, undesirable patch panel connections, and connecting a lot of cables with each other as other factors for clocking troubles. Nonetheless, the number 1 reason behind clocking troubles in my knowledge is just forgetting to configure the clockrate command!