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Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
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Chapter 10 Configuring VLANs
Configuring Auxiliary VLANs
Caution When you delete a VLAN, any ports that are assigned to that VLAN become inactive. Such ports remain
associated with the VLAN (and thus, inactive) until you assign them to a new VLAN.
To delete a VLAN on the switch, perform this task in privileged mode:
This example shows how to delete a VLAN (in this case, the switch is a VTP server):
Console> (enable) clear vlan 500
This command will deactivate all ports on vlan 500
in the entire management domain
Do you want to continue (y/n) [n]?y
Vlan 500 deleted
Console> (enable)
Configuring Auxiliary VLANs
The following sections describe how to configure auxiliary VLANs to use with IP phones.
Understanding Auxiliary VLANs
An IP phone contains an integrated three-port 10/100 switch. The ports, which are dedicated
connections, are described as follows:
• Port 1 connects to the Catalyst 4500 series switch or other device that supports Voice-over-IP (VoIP).
• Port 2 is an internal 10/100 interface that carries the phone traffic.
• Port 3 connects to a PC or other device.
Figure 10-2 shows how you can connect a Cisco IP Phone to a Catalyst 4500 series switch.
When the IP phone connects to a 10/100 port on the Catalyst 4500 series switch, the access port
(PC-to-phone jack) of the IP phone can be used to connect a PC.
Packets to and from the PC and to and from the phone share the same physical link to the switch and the
same port of the switch.
Introducing IP-based phones into existing switch-based networks raises the following issues:
• The current VLANs might be configured on an IP subnet basis, and additional IP addresses might
not be available to assign the phone to a port so that it belongs to the same subnet as other devices
(PC) that are connected to the same port.
• Data traffic present on the VLAN supporting phones might reduce the quality of VoIP traffic.
Task Command
Delete a VLAN. clear vlan vlan_num
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