Steven ... correct, by plugging in the PC Port to the switch as well, you would be sending BPDUs back into the switch.
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. = Ryan = ________________________________ From: cisco-voip <cisco-voip-boun...@puck.nether.net> on behalf of Stephen Welsh <stephen.we...@unifiedfx.com> Sent: Thursday, November 10, 2016 8:43 AM To: Ahmed Elnagar Cc: cisco-voip@puck.nether.net Subject: Re: [cisco-voip] IP Phone Ports 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? Kind Regards Stephen Welsh CTO [cid:CBBF0493-235C-43D2-A874-9FB3D95AF598@b2.unifiedfx.com] On 10 Nov 2016, at 13:35, Ahmed Elnagar <ahmed_elna...@hotmail.com<mailto:ahmed_elna...@hotmail.com>> wrote: That is not nice at all :( Did you figure out a way to prevent it from switch side? From: Matthew Loraditch [mailto:mloradi...@heliontechnologies.com] Sent: Thursday, November 10, 2016 3:34 PM To: Ahmed Elnagar <ahmed_elna...@hotmail.com<mailto:ahmed_elna...@hotmail.com>>; 'cisco-voip@puck.nether.net<mailto:cisco-voip@puck.nether.net>' <cisco-voip@puck.nether.net<mailto:cisco-voip@puck.nether.net>> Subject: RE: IP Phone Ports 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. Matthew G. Loraditch - CCNP-Voice, CCNA-R&S, CCDA Network Engineer Direct Voice: 443.541.1518 Facebook<https://www.facebook.com/heliontech?ref=hl> | Twitter<https://twitter.com/HelionTech> | LinkedIn<https://www.linkedin.com/company/helion-technologies?trk=top_nav_home> | G+<https://plus.google.com/+Heliontechnologies/posts> From: cisco-voip [mailto:cisco-voip-boun...@puck.nether.net] On Behalf Of Ahmed Elnagar Sent: Thursday, November 10, 2016 8:28 AM To: 'cisco-voip@puck.nether.net<mailto:cisco-voip@puck.nether.net>' <cisco-voip@puck.nether.net<mailto:cisco-voip@puck.nether.net>> Subject: [cisco-voip] IP Phone Ports Dear all; 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? _______________________________________________ cisco-voip mailing list cisco-voip@puck.nether.net<mailto:cisco-voip@puck.nether.net> https://puck.nether.net/mailman/listinfo/cisco-voip
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