From: Vincent Mashburn (vmashburn@fedex.com)
Date: Wed Mar 22 2006 - 12:30:58 GMT-3
OK. Cool. I see what you are saying now. I have not seen that DHCP
configuration before. Very interesting.
Thanks
Vince Mashburn
Voice / Data Engineer
901-263-5072
Cisco IP Telephony Support Specialist
CCNP, CCDA,Network +
________________________________
From: James Ventre [mailto:messageboard@ventrefamily.com]
Sent: Wednesday, March 22, 2006 9:28 AM
To: Vincent Mashburn
Cc: Vishal Patel; david robin; Cisco certification
Subject: Re: Voice vlan
I think we're coming at this from 2 different sides and missing each
other.
My main point is that you don't need to nail up a trunk with the
"switchport mode trunk ...." command if it's a non cisco telephone. You
can still use the voice vlan for it - you just need to figure out what
your options are for telling the telephone what the tagged voice vlan
is.
The below configs I use with an AVAYA telephone. I am feeding the
telephone a trunk. The trunk is created with the following commands
(specifically the "switchport voice vlan 209"):
description { phone and pc }
switchport access vlan 227
switchport mode access
switchport voice vlan 209
service-policy input IP-Telephony
no logging event link-status
no logging event power-inline-status
no mdix auto
storm-control broadcast level 4.00
storm-control multicast level 2.00
no cdp enable
spanning-tree portfast
spanning-tree bpduguard enable
spanning-tree guard root
When the telephone starts up, it DHCP's into the native vlan (because it
doesn't know any better), it gets an IP address and a variable via the
Option 176 field. The variable in the option 176 field is:
L2QVLAN=209. That tells the telephone to tag all of it's traffic with
the 802.1Q VLAN ID of 209. It releases it's DHCP info and re-DHCP's
into VLAN 209 where it gets a new IP address and stays there. The PC
plugged into the back of the telephone uses the untagged vlan and the
telephone uses the tagged vlan it received via DHCP (which matches the
Vlan I setup with the switchport voice vlan xxx).
James
Vincent Mashburn wrote:
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>
> I am not saying that it is totally dependant on CDP. I am just
saying
> that you don't need to configure 802.1q trunks when utilizing a
> complete Cisco environment. The new enhancements to CDP allow voice
> VLAN info to be propagated. Why would this be included if it is
not
> to be used? The Data VLAN is applied to the switchport via
> "switchport access vlan <vlan>" and the voice VLAN is
applied via
> "switchport voice vlan <vlan>". When you are using Cisco
phones and
> using the integrated switchport within the Cisco phone, the VLAN
> information is indeed propagated to the phone via CDP. I know this
> because you configure the switchport as an access port and not a
> trunk port. The phone then assigns the switchport connecting to
the
> PC to the "switchport access vlan <vlan>" and the phone
assigns
> itself to the "switchport voice vlan <vlan>". DHCP can be
utilized
> in this fashion, but I have only been able to get the TFTP server
> info to be propagated to the phones via the option 150 (or option
> 60). I have not seen an option to propagate VLAN information.
Could
> you send me that config? I would be very interested to learn how
to
> do that. Also, whenever I hardcode the voice VLAN on the phone, it
> gets overridden by the CDP propagated voice VLAN.
>
>
>
> Vince Mashburn
>
> Voice / Data Engineer
>
> 901-263-5072
>
> Cisco IP Telephony Support Specialist
>
> CCIE (R&S Written), CCNP, CCDA,Network +
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