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Cisco 1841 with line protocol is down

I have a Cisco 1841 at a remote office. Can't communicate with it. Called the service provider. I asked a non-technical person to do the "Show Interfaces" command and found the serial is up but protocol is down. What is the next step to try when we are waiting for the technical support to call us back?

thank you.

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Re: Cisco 1841 with line protocol is down


There are several things that can produce the symptom of line protocol is down:

- might be a connectivity problem (though if it is connectivity on a serial I would probably expect line is down in addition to line protocol down. But check connectivity as well as you can (given the resources that you may have out there).

- mismatched encapsulation will cause line protocol down. If one end is configured for HDLC and the other is PPP or Frame Relay or something like that it will produce line protocol down. Can you check the encapsulation that is configured on both ends?

- if one end is configured with "no keepalive" that end will be fine but the end that is still doing keepalives will be line protocol down. Can you find if for any reason the other end of the serial is configured with no keepalive?

- if there is a problem with clocking it would produce line protocol down. is there configuration of clocking (clock source) on the serial?

My first guess would be mis-matched encapsulation. I would check on that first.



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