[cisco-voip] Serial interface state change

[Mike King]

Hi Fred,

When you downed Se0/0/0:23, you downed 1 channel on the PRI. leaving the
other 23 channels up.  The PRI was still up. You just downed the channel
that has the D-Channel on it.  The reason it came backup is your Service
providor received an alarm on they're side showing your PRI was down.  I'm
assuming after a unspecified amount of time, they bounced the entire PRI to
bring the channels back up. (That would the the AIS detected message, it's
a test message)

Downing the controller is the correct way to do this/

Mike


On Wed, Apr 10, 2013 at 4:14 PM, Fred Hunt <FHunt at erdman.com> wrote:

>  I’m trying to figure out why a serial interface seemingly changed its
> state on its own.****
>
>
> We have a PRI that we are planning to decommission.  I previously removed
> it from being routed to in CUCM and I shut down the serial0/0/0:23
> interface, as shown in the log below:****
>
> 021241: Mar 16 20:32:48.963 CDT: %ISDN-6-LAYER2DOWN: Layer 2 for Interface
> Se0/0/0:23, TEI 0 changed to down****
>
> 021242: Mar 16 20:32:50.960 CDT: %LINK-5-CHANGED: Interface
> Serial0/0/0:23, changed state to administratively down****
>
> ** **
>
> Then, somehow the serial interface changed its state back to up.  This
> occurred after what appeared to be a brief outage of the T1 service.
> Here’s the relevant log detail:****
>
> 021244: Mar 18 10:25:16.673 CDT: %CONTROLLER-5-UPDOWN: Controller T1
> 0/0/0, changed state to down (AIS detected)****
>
> 021245: Mar 18 10:25:16.881 CDT: %MARS_NETCLK-3-HOLDOVER: Entering
> Holdover for Controller T1 0/0/0****
>
> 021246: Mar 18 10:25:18.673 CDT: %LINK-3-UPDOWN: Interface Serial0/0/0:23,
> changed state to down****
>
> 021247: Mar 18 10:25:20.673 CDT: %CONTROLLER-5-UPDOWN: Controller T1
> 0/0/0, changed state to up****
>
> 021248: Mar 18 10:25:22.189 CDT: %LINK-3-UPDOWN: Interface Serial0/0/0:23,
> changed state to up****
>
> 021249: Mar 18 10:25:23.133 CDT: %MARS_NETCLK-3-HOLDOVER: Exiting Holdover
> for Controller T1 0/0/0****
>
> 021250: Mar 18 10:25:24.917 CDT: %ISDN-6-LAYER2UP: Layer 2 for Interface
> Se0/0/0:23, TEI 0 changed to up****
>
> ** **
>
> Today, I discovered that the interface was up and shut it down again.
> Then I decided to shutdown the controller itself.  Here’s the log:****
>
> 021310: Apr 10 13:57:23.272 CDT: %LINK-5-CHANGED: Interface
> Serial0/0/0:23, changed state to administratively down****
>
> 021312: Apr 10 14:13:28.404 CDT: %CONTROLLER-5-UPDOWN: Controller T1
> 0/0/0, changed state to administratively down****
>
> 021313: Apr 10 14:13:28.424 CDT: %MARS_NETCLK-3-HOLDOVER: Entering
> Holdover for Controller T1 0/0/0****
>
> 021314: Apr 10 14:13:30.404 CDT: %LINK-3-UPDOWN: Interface Serial0/0/0:23,
> changed state to down****
>
> ** **
>
> I observed that after shutting the controller down the state of
> serial0/0/0:23 changed from administratively down to down.  I’m guessing
> that this will stick now, but I’m not sure after the earlier behavior.  I
> don’t understand how the serial interface was able to previously change its
> layer 1 state on its own.  Don’t both administratively down and down mean
> down at the layer 1 level?  Does a router automatically reset the state of
> serial interfaces if their associated T1 controller changes from the down
> to up state?****
>
> ** **
>
> Thanks,****
>
> Fred****
>
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