[cisco-voip] cisco IP Phone causes stp loop.

[Lee Pedder]

I can't offer specific advice on the CE500 switch, but on other cisco
switches there is a bpduguard feature that you need to enable if you
are using spanning-tree portfast. This will shutdown a port on receipt
of a BPDU (such as one received from itself on another port).

On 04/07/07, Jefflin Choi <jefflin.choi at gmail.com> wrote:
> Ahmed,
>
> The users are using PC connected to the IP phones. Someone non-technical
> plugged both connections to the switch instead of one cable to the PC.
>
> Educating end users to plug the ip phones to the correct devices is simple
> but this is a security risk which can cause sabotage of the network.
>
> Matt,
>
> I do not see how "Try turning off GARP on the phone, disable web access and
> turn off voice vlan access." can help. Can you explain why this will help
> solve the problem.
>
> First, web access can be disabled. No problem with it. I can't see the
> relation with the loop though.
>
> second voice vlan access, you mean to say not to allow the voice vlan on the
> trunk?
>
> Thanks,
> Jeff
>
>
>
>
> On 7/4/07, Ahmed Elnagar <aelnagar at act-eg.com> wrote:
> >
> >
> >
> > Well, I was not trying to answer the Q. I was just sharing my dislikeness
> of this switch as I had alot o problems with it :), sepically with vlans
> trunking. I had it running with IP Phones normally with no problem.
> changeing the port role on the switch sometimes it helps, but I dont think
> in ur case. but what I got from ur words seems that the users is not using a
> PC connected to th phone (otherwise they will connect 2 cables from the
> switch) if that is the case try to disable the PC port of the IP Phone.
> >
> >
> >
> > Thanks and Best Regards
> >
> > Ahmed A. Elnagar
> > Network Engineer Specialist
> >
> > Advanced Computer Technology (ACT)
> > 16 Fawzy Ramah St.Off Shehab St.Mohandessin, Giza, Egypt
> > Postal Code:12411 Cairo Egypt
> >
> > Mob : +2010-2833868
> > Website: www.act-eg.com
> > E-mail: aelnagar at act-eg.com
> >
> > ________________________________
>  From: cisco-voip-bounces at puck.nether.net on behalf of Matt
> Slaga (US)
> > Sent: Tue 03-Jul-07 3:25 PM
> > To: Ahmed Elnagar; Jefflin Choi; cisco-voip at puck.nether.net
> > Subject: Re: [cisco-voip] cisco IP Phone causes stp loop.
> >
> >
> >
> >
> >
> > Wow, that reply should help you solve that problem lickety split!
> >
> >
> >
> > Try turning off GARP on the phone, disable web access and turn off voice
> vlan access.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > From: cisco-voip-bounces at puck.nether.net
> [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of
> Ahmed Elnagar
> > Sent: Tuesday, July 03, 2007 3:25 AM
> > To: Jefflin Choi; cisco-voip at puck.nether.net
> > Subject: Re: [cisco-voip] cisco IP Phone causes stp loop.
> >
> >
> >
> > Just a note
> >
> > I Hate 500 Express it is a very bad switch and it has a lot of strange
> configuration setting plus no useful troubleshooting capabilities at all.
> >
> >
> >
> > ________________________________
>
> >
> > From: cisco-voip-bounces at puck.nether.net
> [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of
> Jefflin Choi
> > Sent: Tuesday, July 03, 2007 9:56 AM
> > To: cisco-voip at puck.nether.net
> > Subject: [cisco-voip] cisco IP Phone causes stp loop.
> >
> >
> >
> >
> > Hi all,
> >
> >
> >
> >
> >
> > Some end user plugged the pc port and switch port of an IP Phone to a
> Catalyst CE500 port at the same time causing our client's switch on a loop.
> >
> >
> >
> >
> >
> > CE500--------7912 IP Phone
> >
> >
> >   |                        |
> >
> >
> >   |------------------------|
> >
> >
> >
> >
> >
> >
> > We can't prevent end user making accidental mistakes like this which might
> cause network failure.
> >
> >
> >
> >
> >
> > I was wondering if Cisco IP phones are sending BPDU so that the CE500 will
> errdisable the port. Doesn't it?
> >
> >
> >
> >
> >
> > Any way to prevent the this from happening?
> >
> >
> >
> >
> >
> > Thanks,
> >
> >
> > Jeff
> >
> >
> >
> >
> > ________________________________
>
> >
> >
> >
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>
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