From: adz (ccie1day@totalise.co.uk)
Date: Tue Mar 18 2003 - 17:28:30 GMT-3
david,
I don't know the answer either, but this is my theory...I hope that it will
prompt other "listers" to post there understandings!
A big disclamer - if this is wrong, please accept my appologies in advance
1. ip phone talks CDP with the switch, the switch therefore knows the mac
address of the phone.
2a. when you configure a voice vlan on the 3550, (or auxilary vlan on a
catos switch,) the switch matches the ip phone mac addess to this vlan
2b. the ip phone also knows about the voice vlan so it capable of tagging
frames.
3. traffic from the pc will be clear, so you can use either a. switch port
access vlan 10 OR b. 802.1q TRUNK with native vlan 10
if you choose to use the dot1q trunk method then presumably the IP phone can
set the trunking qos parameters so this is the better option
BUT i was reading an avvid document:
http://www.cisco.com/application/pdf/en/us/guest/netsol/ns17/c649/ccmigratio
n_09186a00800d67ed.pdf (file attached)
in this document it sets out what to do with IP phones on
a 6500's
b 4003
c. 3550 !!!!!!
d. 3524XL
e. 2950
in this example, they use trunking on the 3524XL, but not on the 3550???
I think this is because the 3924XL is a pure L2 switch as as a result relies
on an external router to covert between cos and qos in a contoller manner. I
this instance you would need the extra cos values that you can configure on
trunks.
Because the 3550 is a l2/l3 switch, this cos/qos mapping is done locally and
you don't need the extra l2 cos.
corrections please......
4003-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
David Terry (ETL)
Sent: 18 March 2003 17:28
To: 'Ccielab@Groupstudy.Com'
Subject: Voice Vlan
Dear all,
I am reading the 3550 command reference at the moment and I am confused
regarding the voice vlan.
I have searched the archives but can't find a definitive answer.
If I have a PC hanging off the back an IP phone which is connecting to a
3550. The PC belongs to say vlan 10
1) Can I configure a voice vlan and use 802.1p on the same switch port as
well as letting the PC still have connectivity to it's vlan ?
2) Would I need to configure the switch to IP phone link as an access port
or a trunk?
The Cisco command reference is a bit ambiguous saying access port and then
mentions 802.1q
Any help would be much appreciated
Many thanks in advance.
David
[GroupStudy removed an attachment of type application/pdf which had a name of ccmigration_09186a00800d67ed.pdf]
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