Cisco 4321 router wan port issue

[Ramanshu]

Branch Router(cisco ISR4321/K9) is currently working on secondary link and the primary interface is having issue. After taking console of the router we found there was logs getting generated continuously saying serial 1/0/1 is down and serial 1/0/1 is up. we tried doing shut no shut, also rebooted the router but no luck then we removed the serial interface then also the logs did not stop that was strange.

Cisco IOS Software Version 15.5(3)S4b, RELEASE SOFTWARE (fc1)

Kindly suggest

[Daniele Giordano]

Hi, can you post the output of show log, show ver, show interface seriale 1/0/1, show run int serial 1/0/1?

Regards.

[Ramanshu]

Corrections- its serial 0/1/0 and not 1/0/1, please ignore the post mistake

Yes sure, i have got the show tech and filtered out the outputs which you asked for:

Show interface serial 0/1/0, show logging, show version, show run int serial 0/1/0

PFA.

Thanks in advance.

[mcusine]

Hi,

I saw dcd down on your show this maybe indicate line or modem problem.

Check this other theread maybe will usefull.

https://community.cisco.com/t5/routing/dcd-down/td-p/1835339

Regards.

[Daniele Giordano]

I don't understand if you see the error logs also without the serial interface inserted into the router.

Regards.