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<p>Steven ... correct, by plugging in the PC Port to the switch as well, you would be sending BPDUs back into the switch.</p>
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<p>So as long as BPDU guard is enabled on the switch ports, then doing this would err-disable both switch ports (the one the PC Port and Network Port is plugged into). Pretty easy at that point to tell who the culprit is remotely, and in person.</p>
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<p>= Ryan =<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" color="#000000" face="Calibri, sans-serif"><b>From:</b> cisco-voip <cisco-voip-bounces@puck.nether.net> on behalf of Stephen Welsh <stephen.welsh@unifiedfx.com><br>
<b>Sent:</b> Thursday, November 10, 2016 8:43 AM<br>
<b>To:</b> Ahmed Elnagar<br>
<b>Cc:</b> cisco-voip@puck.nether.net<br>
<b>Subject:</b> Re: [cisco-voip] IP Phone Ports</font>
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<div class="">I thought that this would be prevented by default because of spanning tree/BPDU, but it’s common practice to disable spanning tree for access ports (i.e. using portfast) so that may allow the loop to occur, so maybe just disable port-fast?</div>
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<div class="">Kind Regards</div>
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Stephen Welsh</div>
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CTO</div>
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<div class="">On 10 Nov 2016, at 13:35, Ahmed Elnagar <<a href="mailto:ahmed_elnagar@hotmail.com" class="">ahmed_elnagar@hotmail.com</a>> wrote:</div>
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<span class="" style="color:rgb(31,73,125)">That is not nice at all<span class="Apple-converted-space"> </span></span><span class="" style="font-family:Wingdings; color:rgb(31,73,125)">L</span><span class="" style="color:rgb(31,73,125)"></span></div>
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<span class="" style="color:rgb(31,73,125)">Did you figure out a way to prevent it from switch side?</span></div>
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<b class="">From:</b><span class="Apple-converted-space"> </span>Matthew Loraditch [<a href="mailto:MLoraditch@heliontechnologies.com" class="">mailto:MLoraditch@heliontechnologies.com</a>]<span class="Apple-converted-space"> </span><br class="">
<b class="">Sent:</b><span class="Apple-converted-space"> </span>Thursday, November 10, 2016 3:34 PM<br class="">
<b class="">To:</b><span class="Apple-converted-space"> </span>Ahmed Elnagar <<a href="mailto:ahmed_elnagar@hotmail.com" class="">ahmed_elnagar@hotmail.com</a>>; '<a href="mailto:cisco-voip@puck.nether.net" class="">cisco-voip@puck.nether.net</a>' <<a href="mailto:cisco-voip@puck.nether.net" class="">cisco-voip@puck.nether.net</a>><br class="">
<b class="">Subject:</b><span class="Apple-converted-space"> </span>RE: IP Phone Ports</div>
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<span class="" style="color:rgb(31,73,125)">Yes it will create a loop. Not a fun time trying to track these things down. I’ve had some non-Cisco IP phones completely down a LAN.</span></div>
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<span class="" style="font-size:10pt; color:rgb(31,73,125)">Matthew G. Loraditch – CCNP-Voice, CCNA-R&S, CCDA<br class="">
Network Engineer<br class="">
Direct Voice: 443.541.1518</span><span class="" style="color:rgb(31,73,125)"></span></p>
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<span class="" style="color:rgb(31,73,125)"><a href="https://www.facebook.com/heliontech?ref=hl" class="" style="color:rgb(149,79,114); text-decoration:underline"><span class="" style="font-size:8pt; color:blue">Facebook</span></a></span><span class="" style="font-size:8pt; color:rgb(31,73,125)"><span class="Apple-converted-space"> </span>|<span class="Apple-converted-space"> </span></span><span class="" style="color:rgb(31,73,125)"><a href="https://twitter.com/HelionTech" class="" style="color:rgb(149,79,114); text-decoration:underline"><span class="" style="font-size:8pt; color:blue">Twitter</span></a></span><span class="" style="font-size:8pt; color:rgb(31,73,125)"><span class="Apple-converted-space"> </span>|<span class="Apple-converted-space"> </span></span><span class="" style="color:rgb(31,73,125)"><a href="https://www.linkedin.com/company/helion-technologies?trk=top_nav_home" class="" style="color:rgb(149,79,114); text-decoration:underline"><span class="" style="font-size:8pt; color:blue">LinkedIn</span></a></span><span class="" style="font-size:8pt; color:rgb(31,73,125)"><span class="Apple-converted-space"> </span>|<span class="Apple-converted-space"> </span></span><span class="" style="color:rgb(31,73,125)"><a href="https://plus.google.com/+Heliontechnologies/posts" class="" style="color:rgb(149,79,114); text-decoration:underline"><span class="" style="font-size:8pt; color:blue">G+</span></a></span></div>
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<b class="">From:</b><span class="Apple-converted-space"> </span>cisco-voip [<a href="mailto:cisco-voip-bounces@puck.nether.net" class="" style="color:rgb(149,79,114); text-decoration:underline">mailto:cisco-voip-bounces@puck.nether.net</a>]<span class="Apple-converted-space"> </span><b class="">On
Behalf Of<span class="Apple-converted-space"> </span></b>Ahmed Elnagar<br class="">
<b class="">Sent:</b><span class="Apple-converted-space"> </span>Thursday, November 10, 2016 8:28 AM<br class="">
<b class="">To:</b><span class="Apple-converted-space"> </span>'<a href="mailto:cisco-voip@puck.nether.net" class="">cisco-voip@puck.nether.net</a>' <<a href="mailto:cisco-voip@puck.nether.net" class="" style="color:rgb(149,79,114); text-decoration:underline">cisco-voip@puck.nether.net</a>><br class="">
<b class="">Subject:</b><span class="Apple-converted-space"> </span>[cisco-voip] IP Phone Ports</div>
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Dear all;</div>
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I want to know what will happen if a user connect “by mistake” both the PC port and Switch port to the network switch? Will this create a loop? Anyone tried it before?</div>
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