Cisco CCNA / CCNP Certification Examination: Troubleshooting Direct Serial Connections
A major topic of one's CCNA and CCNP CIT exams is going to be connecting Cisco routers right by means of their Serial interfaces, and even though the configuration is simple, there are numerous essential specifics and display instructions you must know so that you can go the exams and configure this correctly in generation and home lab networks. Permit’s Consider a sample configuration.
Connecting Cisco routers directly via their Serial interfaces performs rather well when you get it managing – and acquiring such a link up and functioning is not difficult enough. You need to use show controller serial x 인스타 좋아요 to determine which endpoint is performing as https://en.wikipedia.org/wiki/?search=인스타 팔로워 구매 the DCE, and it’s the DCE that need to be configured Along with the clockrate command.
R3#present controller serial one
HD unit 1, idb = 0x11B4DC, driver construction at 0x121868
buffer sizing 1524 HD unit 1, V.35 DCE cable
R3(config)#int serial1
R3(config-if)#ip tackle 172.twelve.13.3 255.255.255.0
R3(config-if)#clockrate 56000
R3(config-if)#no shut
Failure to configure the clockrate has some intriguing effects concerning the physical and sensible condition of the interfaces. Let’s take away the clockrate from R3 and find out what takes place.
R3(config)#int s1
R3(config-if)#no clockrate 56000
R3(config-if)#
eighteen:02:19: %LINEPROTO-five-UPDOWN: Line protocol on Interface Serial1, transformed point out to down
The line protocol doesn’t drop promptly, but it really does drop. Allow’s run exhibit interface serial1 to match the physical and rational interface states.
R3#present int serial1
Serial1 is up, line protocol is down
Physically, the interface is ok, And so the physical interface is up. It’s only the logical Component of the interface – the line protocol – that may be down. It’s precisely the same condition on R1.
R1#display inter serial1
Whilst a router misconfiguration could be the probably cause of a serial link challenge, that’s not the only real basis for clocking problems. Cisco’s Site documentation mentions CSU/DSU misconfiguration, out-of-spec cables, poor patch panel connections, and connecting a lot of cables alongside one another as other good reasons for clocking problems. However, the number one basis for clocking issues in my working experience is actually forgetting to configure the clockrate command!