Chapter 55 Configuring a VoIP Network

Configuring VoIP on a Switch

Auxiliary VLAN Configuration Guidelines

This section describes the guidelines for configuring the auxiliary VLANs:

An auxiliary VLAN port is operationally a trunk, even though it is not treated like a “normal” trunk port. When an auxiliary VLAN is added to a port and the set dot1q-all-taggedcommand is enabled, the set dot1q-all-taggedcommand tags the native VLAN on the port where the auxiliary VLAN is configured. A port with an auxiliary VLAN configured is not viewed as an 802.1Q trunk in the show trunk command output, but the port acts like an 802.1Q trunk if the set dot1q-all-taggedcommand is enabled.

The IP phone and a device that is attached to the phone are in the same VLAN and must be in the same IP subnet if one of the following occurs:

They use the same frame type.

The phone uses 802.1p frames, and the device uses untagged frames.

The phone uses untagged frames, and the device uses 802.1p frames.

The phone uses 802.1Q frames, and the auxiliary VLAN equals the native VLAN.

The IP phone and a device that is attached to the phone cannot communicate if they are in the same VLAN and subnet but use different frame types, because the traffic between the devices in the same subnet is not routed (routing would eliminate the frame type difference).

You cannot use the switch commands to configure a frame type that is used by the traffic that is received from a device that is attached to the phone’s access port.

With software release 6.2(1) and later releases, the dynamic ports can belong to two VLANs—a native VLAN and an auxiliary VLAN. See Chapter 19, “Configuring Dynamic Port VLAN Membership with VMPS,” for the configuration details for the auxiliary VLANs.

Configuring the Auxiliary VLANs

To configure the auxiliary VLANs, perform this task in privileged mode:

Task

Command

 

 

Configure the auxiliary VLANs.

set port auxiliaryvlan mod[/ports] {vlan

 

untagged dot1p none}

 

 

This example shows how to add the voice ports to the auxiliary VLANs, specify an encapsulation type, or specify that the VLAN will not send or receive CDP messages with voice-related information:

Console> (enable)

set port auxiliaryvlan 2/1-3 222

Auxiliaryvlan

222

configuration successful.

AuxiliaryVlan

AuxVlanStatus

Mod/Ports

-------------

-------------

-------------------------

222

active

1/2,2/1-3

Console> (enable)

set port auxiliaryvlan 5/7 untagged

Port 5/7 allows the connected device send and receive untagged packets and without 802.1p priority.

Console> (enable) set port auxiliaryvlan 5/9 dot1p

Port 5/9 allows the connected device send and receive packets with 802.1p priority. Console> (enable) set port auxiliaryvlan 5/12 none

Port 5/12 will not allow sending CDP packets with Voice VLAN information. Console> (enable)

 

 

Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7

 

 

 

 

 

 

OL-8978-02

 

 

55-21

 

 

 

 

 

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Cisco Systems OL-8978-02 Auxiliary Vlan Configuration Guidelines, Configuring the Auxiliary VLANs, Untagged dot1p none

OL-8978-02 specifications

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