Cisco CCNA / CCNP Certification Examination: Troubleshooting Direct Serial Connections
A first-rate subject matter within your CCNA and CCNP CIT exams will probably be connecting Cisco routers right through their Serial interfaces, and although the configuration is simple, there are some critical particulars and exhibit commands you have to know to be able to go the examinations and configure this effectively in production and residential lab networks. Permit’s Examine a sample configuration.
Connecting Cisco routers instantly through their Serial interfaces works very well when you finally get it working – and getting this type of connection up and jogging is easy plenty of. You should use exhibit controller serial x to understand which endpoint is acting 인스타 팔로워 구매 as being the DCE, and it’s the DCE that should be configured Using the clockrate command.
R3#demonstrate controller serial 1
HD unit one, idb = 0x11B4DC, driver construction at 0x121868
buffer dimension 1524 High definition device 1, https://en.search.wordpress.com/?src=organic&q=인스타 팔로워 구매 V.35 DCE cable
R3(config)#int serial1
R3(config-if)#ip tackle 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 fascinating effects concerning the physical and logical point out of your interfaces. Allow’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-5-UPDOWN: Line protocol on Interface Serial1, improved condition to down
The road protocol doesn’t fall quickly, but it surely does fall. Let’s run exhibit interface serial1 to compare the physical and sensible interface states.
R3#present int serial1
Serial1 is up, line protocol is down
Bodily, the interface is okay, Therefore the Actual physical interface is up. It’s only the sensible part of the interface – the road protocol – that is certainly down. It’s exactly the same scenario on R1.
R1#demonstrate inter serial1
Although a router misconfiguration will be the most likely explanation for a serial link situation, that’s not the only reason behind clocking concerns. Cisco’s Web site documentation mentions CSU/DSU misconfiguration, out-of-spec cables, terrible patch panel connections, and connecting too many cables alongside one another as other good reasons for clocking complications. Even now, the number 1 cause of clocking troubles in my experience is simply forgetting to configure the clockrate command!