CCNA exam achievement depends largely on noticing the details, which is very true of configurations involving straight connected serial interfaces. And of course, http://query.nytimes.com/search/sitesearch/?action=click&contentCollection®ion=TopBar&WT.nav=searchWidget&module=SearchSubmit&pgtype=Homepage#/먹튀검증 it’s not adequate to note these aspects – you’ve acquired to understand how to proceed about them!
A Cisco router can be a DTE by default, but immediately connecting two DTEs using a DCE/DTE cable is not really enough. In the next example, R1 and R3 are straight connected at their Serial1 interfaces. The road goes up briefly right after being opened, but the road protocol goes down just after about 30 seconds.
R3(config-if)#int s1
R3(config-if)#ip address 172.twelve.13.3 255.255.255.0
R3(config-if)#no shutdown
2d18h: %Backlink-three-UPDOWN: Interface Serial1, altered state to up
2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, modified state to up
R3(config-if)#
2d18h: %LINEPROTO-five-UPDOWN: Line protocol on Interface Serial1, modified state to down
The situation is the fact that one of several routers must act as being the DCE in order for the road protocol to return up and stay awake. If this ended up your CCNA / CCNP property lab, you could just go around and look at the DTE/DCE cable to determine which router had the DCE conclude on the cable connected. In this instance, although, we don’t have Actual physical usage of the routers. How can we inform which router has the DCE conclude of your cable connected?
R3#present controller serial one
High definition device one, idb = 0x1C44E8, driver framework at 0x1CBAC8
buffer size 1524 HD unit one, V.35 DCE cable
The clearly show controller command gives us this facts. (There’s quite a bit much more output that this with this particular command, nevertheless it’s unimportant for our needs.) The router While using the DCE end with the cable requirements to produce a clock fee towards the DTE, and we’ll https://mthunter87.com/ do exactly that While using the interface-level clockrate command.
R3#conf t
Enter configuration commands, 1 for each line. Conclusion with CNTL/Z.
R3(config)#int serial1
R3(config-if)#clockrate 56000
In just a couple seconds, the line protocol goes up and stays up.
When troubleshooting a relationship, usually operate exhibit interface very first. If the thing is The mix revealed under, the link is bodily high-quality but logically down. That’s generally the results of a essential keepalive not currently being existing. With Body Relay, it’s likely an LMI problem, but with specifically related serial interfaces The problem is almost certainly the DCE conclude from the connection not supplying clockrate.
R3#show interface serial 1
Serial1 is up, line protocol is down
Troubleshooting is a large A part of the job, and it’s a giant Portion of the Cisco CCNA and CCNP courses too. Know your exhibit and debug commands and also you’re in your solution to passing the CCNA!