01-14-2009 05:48 PM - edited 03-15-2019 03:31 PM
hi guys
dose cisco IP phone can disable the pc port automatically when it detects a loopback on the phone.
for eg: if two cable from the back of the phones are plugged in to the switch.
Nortel phones can do that... not sure about cisco..
thanks
01-14-2009 05:52 PM
Hello,
I dont believe the PC port will be disabled automatically if the switch detects a bridging loop. I have had several customers to which this has happened, and we had to end up configuring port security on the switchports so that the port that detects the loop will go into error disabled mode.
Hope that helped, if so please rate.
01-14-2009 05:54 PM
hi Kenneth
i was thinking about kind of port security
but whihc otion will be helpful in this case
is it max mac or what
thanks anyway
01-14-2009 06:09 PM
Off the top of my head, I believe we did something like the following:
switchport port-security maximum 2
switchport port-security
switchport port-security aging time 1
and
storm-control broadcast level 50.00
storm-control action trap
spanning-tree portfast
spanning-tree bpduguard enable
This seems to have remedied the issue. When the port detects a 3rd mac address, it goes into error disabled mode. However, beware, as things may break if you have users randomly moving computers and phones around by themselves. By the way, this was on some 3750 switches.
Hope that helped, if so please rate.
01-15-2009 05:36 AM
The reason this happens is because having switches behind the phones is not supported - thus we have not programmed any switch-level protection into the phones.
Like kenneth mentioned, you would want to enable BPDU guard on phone ports to make sure you do not receive BPDU's. Likewise, configure the switch behind the phone not to send out BPDU's to the phones.
hth,
nick
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