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Community Member

Loop with IP Phone

I ahve been facing a wierd problem with cisco IP phones.

It happens when a user connects both the switch & the PC port cable to the switch therby causing a loop.

can anyone let me know how to quickly find out which phone is connected in that way.

thanks in advance

4 REPLIES

Re: Loop with IP Phone

Hi

In a normal scenario one cable should come from switch to ip phone and from ip phone it should go to the PC.

If u bring to cables n plug them in the IP phone it will create a loop as the ip phones have a built in switch like arcitecture.

Thanks

Mahmood

Community Member

Re: Loop with IP Phone

I know the phone behaves as a switch.

What I need to know is a way to find out which phone is exactly connected in this way.

users dont understand the switch loop function and itsdifficult for me to search a specific phone connected that way.

thanks in advance

Re: Loop with IP Phone

Hi

Do u see any host flapping messages on ur switch.There u can find out on which ports the loop is created.

One more thing to check the cdp nei on ur switches from there u can find if u get the same neighbor on two ports.

Thanks

Mahmood

Re: Loop with IP Phone

I'm not clear about the way the phone is creating the loop. You mean that both phone ports are connected to the same switch? If this is the case and STP is still running on the switch, it should block one of its port and put it in backup role (likely to be alternate if the phone is connected to two different switches). By checking the role of your access ports, you should be able to easily identify which ones are looped back through a phone.

Regards,

Francois

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