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CSCut26167, fixed in 10.3.1.
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<div class=""><a href="https://tools.cisco.com/bugsearch/bug/CSCut26167" class="">https://tools.cisco.com/bugsearch/bug/CSCut26167</a></div>
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<pre style="widows: 1; white-space: pre-wrap; word-wrap: break-word;" class=""></pre>
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<pre style="widows: 1; white-space: pre-wrap; word-wrap: break-word;" class=""><b style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px;" class="">Symptom:</b></pre>
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<blockquote type="cite"><span style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">A switching loop occurs when an 88xx phone has its network and PC port connected to the switch when
the phone does not forward the BPDU</span><br style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">
<br style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">
<b style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">Conditions:</b><br style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">
<span style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">This has been found to occur on switches using MST. With other types of spanning tree, this issue has not been observed.</span><br style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">
<br style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">
<b style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">Workaround:</b><br style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">
<span style="color: rgb(68, 68, 68); font-family: Arial, Helvetica, sans-serif; line-height: 15.9996004104614px; widows: 1;" class="">Do not use MST, or use another phone model.</span></blockquote>
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<div class="">-Ryan </div>
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<div class="">On Jul 8, 2015, at 2:47 PM, Michael David <<a href="mailto:mdavid@sps186.org" class="">mdavid@sps186.org</a>> wrote:</div>
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<div class="">Just a heads up to anyone running 8800-series phones and using MSTP.
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We're in deployment of a new 10.5 CUCM system with 8851 and 7841 phones. A few times now we've been hit with network loops as janitors empty rooms to clean/wax and then replace stuff, plugging in everything they see loose. The loops have only been happening
with 8851 phones. With the 7841 phones, bpduguard shuts down the phone almost as soon as connected. With the 8851s, the loop runs unchecked.. and affects the entire site, almost like the phone is filtering BPDUs. However, I took a phone and switch into the
lab, and after a little testing have found that the problem only occurs when using MSTP.<br class="">
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Switch: WS-C2960XR-48FPD-I<br class="">
Switch firmware: 10.0(2)EX5<br class="">
Phone firmware: 10.2(2)<br class="">
Test case log: <a href="http://pastebin.com/gm5emaZa" class="">http://pastebin.com/gm5emaZa</a><br class="">
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I can't currently test this with the 10.3 firmware, but I saw no mention of spanning tree in the 10.3 release notes. In the short term, I'll probably have to switch all of our switches to rapid-pvst. Convergence with non-cisco equipment will be slower, but
that's the lesser evil here. Hope I've saved someone else some grief. :-)<br class="">
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Michael<br class="">
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--<br class="">
Michael A. David, CCNA <br class="">
Springfield Public Schools<br class="">
Technology Service Center<br class="">
217.585.5802 ext. 85114<br class="">
217.585.5809 (FAX)<br class="">
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