Cisco CCNA / CCNP Certification Test: Troubleshooting Direct Serial Connections
A main subject of the CCNA and CCNP CIT tests are going to be connecting Cisco routers right via their Serial interfaces, and whilst the configuration is easy, there are several essential aspects and demonstrate instructions you must know in order to move the exams and configure this efficiently in production and residential lab networks. Let’s Examine a sample configuration.
Connecting Cisco routers directly via their Serial interfaces is effective very well as soon as you get it functioning – and obtaining this type of connection up and running is simple adequate. You should use display controller serial x to learn which endpoint is performing because the DCE, and it’s the DCE that has to be configured Along with the clockrate command.
R3#demonstrate controller serial one
High definition device one, idb = 0x11B4DC, driver structure at 0x121868
buffer dimensions 1524 High definition device one, V.35 DCE cable
R3(config)#int serial1
R3(config-if)#ip handle 172.twelve.13.three 255.255.255.0
R3(config-if)#clockrate 56000
R3(config-if)#no shut
Failure to configure the clockrate has some appealing results concerning the Actual physical and sensible condition from the interfaces. Permit’s take out the clockrate from R3 and see what transpires.
R3(config)#int s1
R3(config-if)#no clockrate 56000
R3(config-if)#
18:02:19: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, improved point out to down
The line protocol doesn’t https://www.washingtonpost.com/newssearch/?query=인스타 팔로워 구매 drop instantly, nonetheless it does drop. Permit’s run present interface serial1 to compare the physical and reasonable interface states.
R3#clearly show read more int serial1
Serial1 is up, line protocol is down
Bodily, the interface is okay, so the physical interface is up. It’s only the sensible Component of the interface – the road protocol – that is definitely down. It’s precisely the same condition on R1.
R1#present inter serial1
Though a router misconfiguration may be the most certainly explanation for a serial connection problem, that’s not the one cause for clocking challenges. Cisco’s website documentation mentions CSU/DSU misconfiguration, out-of-spec cables, negative patch panel connections, and connecting too many cables jointly as other reasons for clocking problems. Continue to, the number 1 reason for clocking challenges in my practical experience is just forgetting to configure the clockrate command!