CCNA exam good results is dependent largely on noticing the main points, which is especially true of configurations involving immediately connected serial interfaces. Not to mention, it’s not plenty of to notice these facts – you’ve got to understand how to proceed about them!
A Cisco router is really a DTE by default, but immediately connecting two DTEs by using a DCE/DTE cable will not be sufficient. In the following example, R1 and R3 are directly linked at their Serial1 interfaces. The line goes up briefly right after becoming 먹튀검증업체 opened, but the road protocol goes down following about 30 seconds.
R3(config-if)#int s1
R3(config-if)#ip tackle 172.12.thirteen.three 255.255.255.0
R3(config-if)#no shutdown
2d18h: %LINK-three-UPDOWN: Interface Serial1, modified state to up
2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, improved state to up
R3(config-if)#
2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, improved state to down
The problem is the fact one of several routers has to act given that the DCE in order for the line protocol to come up and stay awake. If this were your CCNA / CCNP home lab, you can just go above and consider the DTE/DCE cable to find out which router had the DCE close with the cable hooked up. In this instance, although, we don’t have physical access to the routers. How can we explain to which router has the DCE finish of the cable hooked up?
R3#present controller serial 1
High definition unit 1, idb = 0x1C44E8, driver structure at 0x1CBAC8
buffer size 1524 HD device one, V.35 DCE cable
The exhibit controller command offers us this information. (There’s a whole lot a lot more http://edition.cnn.com/search/?text=먹튀검증 output that this with this particular command, nonetheless it’s unimportant for our uses.) The router With all the DCE conclusion on the cable requirements to supply a clock price towards the DTE, and we’ll do exactly that While using the interface-amount clockrate command.
R3#conf t
Enter configuration instructions, 1 per line. Conclusion with CNTL/Z.
R3(config)#int serial1
R3(config-if)#clockrate 56000
In only a few seconds, the road protocol goes up and stays up.
When troubleshooting a relationship, normally run clearly show interface first. If you see the combination revealed under, the connection is physically high-quality but logically down. That’s generally the results of a desired keepalive not staying existing. With Frame Relay, it’s possibly an LMI problem, but with instantly related serial interfaces The difficulty is most probably the DCE close with the connection not providing clockrate.
R3#clearly show interface serial one
Serial1 is up, line protocol is down
Troubleshooting is a huge Component of The work, and it’s a huge Section of the Cisco CCNA and CCNP plans also. Know your exhibit and debug instructions and you’re with your technique to passing the CCNA!