12-16-2014 05:36 PM - edited 03-05-2019 12:23 AM
Hi team
My CISCO1941/K9 show some errors like interface is up but protocol down please check the below log and let me know the possibility of the particular issue
Router#sh interfaces serial 0/1/1
Serial0/1/1 is up, line protocol is down
Hardware is WIC MBRD Serial
Description: $van interface $
Internet address is 117.239.xx.xx/30
MTU 1500 bytes, BW 1544 Kbit/sec, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input 00:00:00, output 00:00:02, output hang never
Last clearing of "show interface" counters 00:21:01
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 1158 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
263 packets input, 3682 bytes, 0 no buffer
Received 263 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
126 packets output, 3024 bytes, 0 underruns
0 output errors, 0 collisions, 42 interface resets
263 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
12-17-2014 12:12 AM
Hello
Check the clocking of the interfaces
One side should be running as DTC and the other as DCE ( this is usually your ISP CPE)
Check cabling also
Can you post:
show run int serial
show controllers | in Serial0/1/1
res
Paul
12-17-2014 05:29 AM
On a serial interface like this line is up line protocol is down is an indication that keepalives have failed. There are several things that can cause this. Paul mentions clocking and that certainly can be a cause. I have seen this symptom when the device on the other end has been configured with "no keepalive" on its interface. I have also seen this symptom when the device on the other end of the connection was configured with a different serial protocol such as PPP or Frame Relay.
HTH
Rick
12-17-2014 11:47 AM
if you cheched the above items then it is very possible your wan interface is crashed
12-12-2019 12:23 PM
Thank you Richard, I had the same problem, the clock rate and DCE/DTE was also good, the only thing that I had to touch was the encapsulation protocol which was misconfigured on one side of my Serial link.
12-13-2019 07:05 AM
Thanks for letting us know. I am glad that my suggestion helped you find the solution for your problem. This community is an excellent place to ask questions and to learn about networking. I hope to see you continue to be active in the community.
HTH
Rick
02-16-2020 02:08 AM
02-16-2020 05:29 AM
I am glad that our suggestions were able to help you solve your problem. Thanks for letting us know. This community is an excellent place to ask questions and to learn about networking. I hope to see you continue to be active in the community.
10-09-2017 08:11 AM
The same is happening with me. As I am connecting two serial interfaces that is of 7609 and 2900 router. Encapsulation is ppp both side and i checked ip addresses too .I am using /30 network
10-09-2017 10:41 AM
You tell us that both sides are specifying PPP so mismatched protocol would not be the cause of your issue. You have not told us whether both sides are specifying keepalive, so that might be a possible cause if one does use keepalive and the other does not. But my guess at the most likely cause if that you have not configured clock rate on the DCE side of the connection.
Perhaps you can post the interface config from both routers and that might help us identify the issue.
HTH
Rick
10-09-2017 12:12 PM
Thanks for the reply. I even tried with the keepalive configuration.. Is there any timer to be configured, because while debugging its pointing towards timer. And can you give the 2900 serial interface mandatory configuration.
Thanks and regards...
Rakesh
10-09-2017 04:58 PM
10-10-2017 10:33 AM
Hi guys.. Thanks for ur advices.. The issue resolved as the interface was faulty and we used another interface.
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