From: Geert Nijs (geert.nijs@simac.be)
Date: Mon Apr 16 2007 - 18:24:58 ART
Hi all,
Looking at the Cisco documentation, the documentation seems to suggest that
the command:
switchport voice vlan dot1p
will put all priority tagged frames into one and the same VLAN (VLAN 0):
switchport voice vlan dot1p
Instruct the switch port to use 802.1P priority tagging for voice traffic and
to use the default native VLAN (VLAN 0) to carry all traffic. By default, the
Cisco IP phone forwards the voice traffic with an 802.1P priority of 5.
(see
http://www.cisco.com/en/US/products/hw/switches/ps646/products_configuration_
guide_chapter09186a00801cdf35.html)
I find this explanation very confusing. It seems to suggest that all priority
tagged frames will be put into the same VLAN.
But first of all, the "native vlan" is not VLAN 0 , but VLAN 1 by default
and according to the DOT1Q standard, VLAN ID 0 is a special vlan, the "null
VLAN".
However, i am looking for Cisco documentation that determines the behaviour of
this command when the access vlan on a port is changed.
So in the case:
interface fa0/1
switchport access vlan 501
switchport voice vlan dot1p
interface fa0/2
switchport access vlan 502
switchport voice vlan dot1p
I cannot find any Cisco documentation that clearly states what will happen
with the voice traffic in this case ?
- will the voice traffic be put into the access vlan of the port ? so 501 for
Fa0/1 and 502 for Fa0/2. So that there is a seperation of the voice traffic of
ports fa0/1 and fa0/2 ?
- or will all voice traffic (priority tagged frames) be put into the same VLAN
? If so, which vlan ? The native vlan ? This is VLAN 1. Will the voice traffic
of both ports be put into the same vlan ?
I have done some tests and it seems that the voice traffic is put inside the
vlan of the access port , but i would like to find some more "official"
documentation regarding this behaviour.
regards,
Geert Nijs
CCIE #13729
This archive was generated by hypermail 2.1.4 : Tue May 01 2007 - 08:28:36 ART