CCNA Examination achievements depends mainly on noticing the small print, and this is very true of configurations involving directly linked serial interfaces. Not to mention, it’s not more than enough to notice these facts – you’ve got to grasp how to proceed about them!
A Cisco router is usually a DTE by default, but right connecting two DTEs which has a DCE/DTE cable will not be more than enough. In the next example, R1 and R3 are immediately linked at their Serial1 interfaces. The line goes up briefly right after currently being opened, but the line protocol goes down following about 30 seconds.
R3(config-if)#int s1
R3(config-if)#ip handle 172.twelve.thirteen.three 255.255.255.0
R3(config-if)#no shutdown
2d18h: %Url-3-UPDOWN: Interface Serial1, altered condition to up
2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, altered state to up
R3(config-if)#
2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, transformed point out to down
The trouble is usually that one of the routers should act because the DCE in order for the road protocol to return up and stay up. If this have been your CCNA / CCNP house lab, you could possibly just go around and look at the DTE/DCE cable to view which router experienced the DCE stop https://www.washingtonpost.com/newssearch/?query=먹튀검증 of your cable connected. In this instance, nevertheless, we don’t have Bodily access to the 안전놀이터 routers. How can we inform which router has the DCE finish on the cable hooked up?
R3#clearly show controller serial one
HD device one, idb = 0x1C44E8, driver framework at 0x1CBAC8
buffer measurement 1524 HD unit 1, V.35 DCE cable
The show controller command presents us this facts. (There’s a good deal much more output this with this command, nonetheless it’s unimportant for our applications.) The router With all the DCE end of the cable demands to produce a clock rate to the DTE, and we’ll just do that While using the interface-stage clockrate command.
R3#conf t
Enter configuration instructions, just one per line. Conclusion with CNTL/Z.
R3(config)#int serial1
R3(config-if)#clockrate 56000
In just a couple seconds, the road protocol goes up and stays up.
When troubleshooting a connection, generally operate display interface to start with. If you see The mix proven under, the connection is physically high-quality but logically down. That’s generally the results of a needed keepalive not becoming existing. With Frame Relay, it’s most likely an LMI challenge, but with instantly connected serial interfaces The problem is most certainly the DCE close with the link not providing clockrate.
R3#present interface serial one
Serial1 is up, line protocol is down
Troubleshooting is a major part of the job, and it’s a giant A part of the Cisco CCNA and CCNP courses too. Know your display and debug instructions and you simply’re on your strategy to passing the CCNA!