CCNA exam accomplishment is dependent largely on noticing the small print, which is especially true of configurations involving specifically connected serial interfaces. Not to mention, it’s not enough to notice these specifics – you’ve obtained to learn how to proceed about them!
A Cisco router is often a DTE by default, but immediately connecting two DTEs by using a DCE/DTE cable is not adequate. In the next illustration, R1 and R3 are instantly linked at their Serial1 interfaces. The road goes up briefly right after currently being opened, but the line protocol goes down after about 30 seconds.
R3(config-if)#int s1
R3(config-if)#ip handle 172.12.thirteen.three 255.255.255.0
R3(config-if)#no shutdown
2d18h: %Hyperlink-3-UPDOWN: Interface Serial1, improved state to up
2d18h: %LINEPROTO-five-UPDOWN: Line protocol on Interface Serial1, altered state to up
R3(config-if)#
2d18h: %LINEPROTO-five-UPDOWN: Line protocol on Interface Serial1, modified point out to down
The condition is that among the routers should act since the DCE to ensure that the road protocol to return up and not sleep. If this were being your CCNA / CCNP property lab, you could potentially just go about and think about the DTE/DCE cable to discover which router had the DCE conclude with the cable attached. In this example, although, we don’t have Actual physical entry to the routers. How can we convey to which router has the DCE finish on the cable hooked up?
R3#present controller serial one
High definition unit one, idb = 0x1C44E8, driver structure at 0x1CBAC8
buffer sizing 1524 High definition device 1, V.35 DCE cable
The clearly show controller command offers us this details. (There’s a whole lot extra output this with this command, but it’s unimportant for our functions.) The router Using the DCE finish from the cable demands to provide a clock fee for the DTE, and we’ll do just that Along https://en.search.wordpress.com/?src=organic&q=먹튀검증 with the interface-level clockrate command.
R3#conf t
Enter configuration instructions, 1 per line. Close with CNTL/Z.
R3(config)#int serial1
R3(config-if)#clockrate 56000
In just some seconds, the road protocol goes up and stays up.
When troubleshooting a connection, constantly operate demonstrate interface to start with. If the thing is The mix revealed below, the link is physically high-quality but logically down. That’s frequently the result of a desired keepalive not getting existing. With Body Relay, it’s most likely an LMI challenge, but with directly connected serial interfaces The problem is 안전놀이터 more than likely the DCE conclude of the connection not providing clockrate.
R3#show interface serial one
Serial1 is up, line protocol is down
Troubleshooting is a giant Component of The task, and it’s a major Section of the Cisco CCNA and CCNP applications also. Know your present and debug commands and you also’re on your approach to passing the CCNA!