PC connectivity problems when connect to a Cat3524XL via an IP phone

Unanswered Question
Apr 19th, 2007
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When we connect a PC to a 7912G IP phone and this one to a Catalyst 3524/48XL using a power injector, the PC doesn't have connectivity. That is, it doesn't receive an IP from DHCP server, but the IP phone runs correctly.

When I delete the config relating to voice (voice vlan, trunk, etc) and I connect the PC directly to the switch it runs correctly too.

This is the config of the port with IP phone:

switchport access vlan 20 (data vlan)

switchport trunk encapsulation dot1q

switchport mode trunk

switchport voice vlan 220 (voice vlan)

spanning-tree portfast

this is the config of the port with only PC:

switchport access vlan 50

spanning-tree portfast

and this is the config of the Gigabit port:

switchport trunk encapsulation dot1q

switchport trunk native vlan 44

switchport mode trunk

Thanks in advance.

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mchandak Fri, 04/20/2007 - 11:48
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7912 phones should not be connected to a trunk port. You should reconfigure the port as access port and configure voice and data vlan ID. With Cisco IP Phones, you can use the port in access mode and have it support 1 Data VLAN and 1 Voice VLAN


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