From: Ken.Farrington@barclayscapital.com
Date: Thu Nov 27 2003 - 09:29:23 GMT-3
Guys, At the risk of repeating questions on this forum, (I did read some of
them) could someone just check out my comments/questions:-
IP Phone (voice) configuration on c3550.
----------------------------------------------------------
The first thing to remember is that you always configure the following two
commands:-
From the Cisco config guide :-
Before you enable voice VLAN, we recommend that you enable QoS on the switch
by
entering the "mls qos" global configuration command and configure the port
trust state
to trust by entering the "mls qos trust cos" interface configuration
command.
Config 1 (trunked)
mls qos
!
interface FastEthernet0/2
switchport access vlan 500
switchport trunk encapsulation dot1q
switchport trunk native vlan 500
switchport mode trunk
switchport voice vlan 501
switchport qos trust cos
no ip address
spanning-tree portfast
!
Config 2 (non-trunked)
mls qos
!
interface FastEthernet0/2
switchport access vlan 500
switchport mode access
switchport voice vlan 501
switchport qos trust cos
no ip address
spanning-tree portfast
!
Questions
What is the difference between these commands
switchport voice vlan 501
or
switchport voice vlan dot1q
Is it, one just uses VLAN 0 as the native VLAN for voice packets and one
uses a specified
"non native" VLAN for voice traffic.
And
If you run the switchport in a non-trunking configuration, how do packets
get differentiated between voice and data as the switchport is in the
non-trunk state and assuming they will not contain an 802.1q field within
the mac header?? Or does the phone always send a packet with the 802.1q tag
inbedded in the mac header? Also in this "non-trunked" configuration, does
the phone also put an 802.1q tag on all packets from the PC or leave them
untagged?
Very sorry if this has been covered before :(
Ken
________________________________________________________________
Ken Farrington
Global Networks, Barclays Capital, 5 The North Colonnade, Canary
Wharf, London, E14 4BB
* Tel : 020 7773 3550
* Mob : 07768-866655
* ken.farrington@barcap.com
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