Problems with Dot1p

From: Gregory Gombas (ggombas@gmail.com)
Date: Sun Nov 18 2007 - 14:20:50 ART

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I tried configuring the voice port on a Cat3560 with dot1p tagging but
get the following error message:

SW1(config-if)# switchport voice vlan dot1p
% Voice VLAN does not exist. Creating vlan 0
SW1(config-if)#
09:23:29: %PM-2-VLAN_ADD: Failed to add VLAN 0 - VLAN not found.

Here is my config:

interface FastEthernet0/22
 switchport mode dynamic desirable
 switchport voice vlan dot1p
 mls qos trust cos
 spanning-tree portfast
!
Couple questions:
1. Why did I get the error message?
2. What is the purpose of vlan 0? I obviously can't add it to my
switch because vlan numbering starts at 1.
3. Why would someone use dot1p instead of manually specifying the
voice vlan number?
4. Documentation states with dot1p configuration the voice and data is
carried in the same vlan, yet from the config examples I've seen the
access vlan is usually configured to be some arbitrary number (say
vlan5) while dot1p is in vlan 0. So how are they in the same vlan?

Thanks,
Greg

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