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

[Jefflin Choi]

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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