Cisco CCNA / CCNP Certification Exam: Troubleshooting Direct Serial Connections
A prime topic of your CCNA and CCNP CIT exams will likely be connecting Cisco routers directly by means of their Serial interfaces, and when the configuration is easy, there are some very important aspects and show instructions it's essential to know in order to move the exams and configure this properly in manufacturing and residential lab networks. Let’s Examine a sample configuration.
Connecting Cisco routers directly through their Serial interfaces is effective really well when you finally get it running – and obtaining such a link up and managing is easy enough. You can utilize present controller serial x to find out which endpoint is acting as being the DCE, and it’s the DCE that have to be configured With all the clockrate command.
R3#present controller serial 1
HD unit one, idb = 0x11B4DC, driver framework at 0x121868
buffer sizing 1524 HD device 1, V.35 DCE cable
R3(config)#int serial1
R3(config-if)#ip http://www.thefreedictionary.com/인스타 팔로워 구매 handle 172.twelve.thirteen.3 255.255.255.0
R3(config-if)#clockrate 56000
R3(config-if)#no shut
Failure to configure the clockrate has some intriguing effects concerning the Bodily and sensible point out with the interfaces. Allow’s clear away the clockrate from R3 and see what occurs.
R3(config)#int s1
R3(config-if)#no clockrate 56000
R3(config-if)#
eighteen:02:19: %LINEPROTO-five-UPDOWN: Line protocol on Interface 인스타 팔로워 Serial1, transformed condition to down
The road protocol doesn’t drop immediately, but it surely does drop. Permit’s operate clearly show interface serial1 to check the physical and sensible interface states.
R3#clearly show int serial1
Serial1 is up, line protocol is down
Bodily, the interface is okay, And so the Bodily interface is up. It’s just the rational Element of the interface – the line protocol – which is down. It’s exactly the same circumstance on R1.
R1#clearly show inter serial1
Even though a router misconfiguration could be the most certainly reason for a serial connection challenge, that’s not the one cause for clocking concerns. Cisco’s Internet site documentation mentions CSU/DSU misconfiguration, out-of-spec cables, poor patch panel connections, and connecting too many cables alongside one another as other factors for clocking challenges. Nevertheless, the number 1 cause of clocking difficulties in my expertise is simply forgetting to configure the clockrate command!