CCNA exam good results relies upon mostly on noticing the main points, and this is especially true of configurations involving straight linked serial interfaces. And naturally, it’s not ample to note these facts – you’ve received to find out what to do about them!
A Cisco router is usually a DTE by default, but immediately connecting two DTEs having a DCE/DTE cable isn't sufficient. In the following case in point, R1 and R3 are straight related at their Serial1 interfaces. The line goes up briefly following currently being opened, but the line protocol goes down immediately after about thirty 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, adjusted condition to up
2d18h: %LINEPROTO-five-UPDOWN: Line protocol on Interface Serial1, adjusted condition to up
R3(config-if)#
2d18h: %LINEPROTO-five-UPDOWN: Line protocol on Interface Serial1, 토토사이트 improved condition to down
The situation is the fact that on the list of routers ought to act since the DCE in order for the line protocol to come back up and not sleep. If this ended up your CCNA / CCNP home lab, you could possibly just go in excess of and think about the DTE/DCE cable to find out which router had the DCE conclusion with the cable hooked up. In this instance, even though, we don’t have Actual physical use of the routers. How can we tell which router has the DCE close in the cable attached?
R3#show controller serial 1
HD device one, idb = 0x1C44E8, driver composition at 0x1CBAC8
buffer dimensions 1524 High definition unit 1, V.35 DCE cable
The exhibit controller command presents https://www.washingtonpost.com/newssearch/?query=먹튀검증 us this data. (There’s quite a bit a lot more output that this with this particular command, but it’s unimportant for our purposes.) The router Using the DCE conclusion of your cable requires to supply a clock level to your DTE, and we’ll do just that with the interface-level clockrate command.
R3#conf t
Enter configuration instructions, just one for every line. End with CNTL/Z.
R3(config)#int serial1
R3(config-if)#clockrate 56000
In just some seconds, the line protocol goes up and stays up.
When troubleshooting a link, normally run present interface initially. If the thing is The mix shown underneath, the relationship is bodily fine but logically down. That’s generally the results of a required keepalive not becoming present. With Body Relay, it’s probably an LMI concern, but with directly linked serial interfaces The problem is most probably the DCE close of your relationship not giving clockrate.
R3#exhibit interface serial one
Serial1 is up, line protocol is down
Troubleshooting is a major Element of The work, and it’s a huge part of the Cisco CCNA and CCNP packages too. Know your exhibit and debug commands so you’re on the technique to passing the CCNA!