serial link

[Robo123]

Hi Team,

i have a cisco 1941 router where the serial link is not coming up.below is the config

tried to reconfigure one by one config .identified when we are applying encapsulation or crypto the link is going up down status.

Please suggest on the above.

[Mark Malone]

whats state is the link in UP/DOWN OR DOWN/DOWN when you do sh ip int ser x/x

do you not need to any chap or pap on the ppp for the ISP to authenticate with ?

[Robo123]

the status is up/down and not using any chap or pap on the ppp for the ISP to authenticate 

[Mark Malone]

that's odd you don't need authentication on an ISP line did they provide you the settings as it needs to match both sides , the issue is the config as its up/down so something is configured wrong

you said when you apply the crypto or ppp config its goes down well that's where you need to start and confirm with the ISP is that the settings they want so you can peer with them

[Felipe A. Amaya]

If you see it up/down, please check your clocking source, it should be set to line.  

[Richard Burts]

If the serial interface is up/down then that means that keepalives are failing. Keepalives could fail because of problems with clock source, they could also fail because of protocol mismatch, because of failure to authenticate, or because of mismatch keepalive setting between the two routers. I suggest that the first thing we need is an understanding of what you are connecting to and how that end is set up and what parameters they expect you to use.

HTH

Rick