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<p class="MsoNormal">I’m trying to figure out why a serial interface seemingly changed its state on its own.<o:p></o:p></p>
<p class="MsoNormal"><br>
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:<o:p></o:p></p>
<p class="MsoNormal">021241: Mar 16 20:32:48.963 CDT: %ISDN-6-LAYER2DOWN: Layer 2 for Interface Se0/0/0:23, TEI 0 changed to down<o:p></o:p></p>
<p class="MsoNormal">021242: Mar 16 20:32:50.960 CDT: %LINK-5-CHANGED: Interface Serial0/0/0:23, changed state to administratively down<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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:<o:p></o:p></p>
<p class="MsoNormal">021244: Mar 18 10:25:16.673 CDT: %CONTROLLER-5-UPDOWN: Controller T1 0/0/0, changed state to down (AIS detected)<o:p></o:p></p>
<p class="MsoNormal">021245: Mar 18 10:25:16.881 CDT: %MARS_NETCLK-3-HOLDOVER: Entering Holdover for Controller T1 0/0/0<o:p></o:p></p>
<p class="MsoNormal">021246: Mar 18 10:25:18.673 CDT: %LINK-3-UPDOWN: Interface Serial0/0/0:23, changed state to down<o:p></o:p></p>
<p class="MsoNormal">021247: Mar 18 10:25:20.673 CDT: %CONTROLLER-5-UPDOWN: Controller T1 0/0/0, changed state to up<o:p></o:p></p>
<p class="MsoNormal">021248: Mar 18 10:25:22.189 CDT: %LINK-3-UPDOWN: Interface Serial0/0/0:23, changed state to up<o:p></o:p></p>
<p class="MsoNormal">021249: Mar 18 10:25:23.133 CDT: %MARS_NETCLK-3-HOLDOVER: Exiting Holdover for Controller T1 0/0/0<o:p></o:p></p>
<p class="MsoNormal">021250: Mar 18 10:25:24.917 CDT: %ISDN-6-LAYER2UP: Layer 2 for Interface Se0/0/0:23, TEI 0 changed to up<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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:<o:p></o:p></p>
<p class="MsoNormal">021310: Apr 10 13:57:23.272 CDT: %LINK-5-CHANGED: Interface Serial0/0/0:23, changed state to administratively down<o:p></o:p></p>
<p class="MsoNormal">021312: Apr 10 14:13:28.404 CDT: %CONTROLLER-5-UPDOWN: Controller T1 0/0/0, changed state to administratively down<o:p></o:p></p>
<p class="MsoNormal">021313: Apr 10 14:13:28.424 CDT: %MARS_NETCLK-3-HOLDOVER: Entering Holdover for Controller T1 0/0/0<o:p></o:p></p>
<p class="MsoNormal">021314: Apr 10 14:13:30.404 CDT: %LINK-3-UPDOWN: Interface Serial0/0/0:23, changed state to down<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Fred<o:p></o:p></p>
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