From: Avner Izhar (aizhar@ccbootcamp.com)
Date: Tue Jun 26 2007 - 04:17:33 ART
Hi,
IMHO, Native vlan is not an access port related attribute, it is a trunk port
attribute.
In your config all traffic will be sent on vlan 300, because it is the access
vlan and this is an access port.
Voice traffic will be marked (for qos purposes) but since the vlan ID will be
0, the marking will be interpreted as matching
to the native vlan (or to the access in our case), and will be tagged as vlan
300 when entering the switch.
There is no reason to config dot1p voice vlan without any qos related commands
like 'mls qos trust cos' and
'switchport priority extend cos 0' . It's not a vlan control mechanism, it's
a qos control one.
-------------------------------------------
Regards,
Avner Izhar
Technical Instructor
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________________________________
From: nobody@groupstudy.com on behalf of Alan Ewer
Sent: Tue 6/26/2007 12:28 AM
To: Cisco certification
Subject: Re: Voice Vlan 0 - DOT1P
Hi Guys..
So I think my misunderstanding relates to the term "native vlan" in relation
to an access port !
I am more familiar with he term native vlan when talking about dot1q
trunks... not access ports .. !!
So..
if the config is
Fas 0/1
switch access vlan 300
switch voice vlan dot1p
the native vlan is going to be Vlan300 ...true ?? and therefore the traffic
will transit the switch as vlan 300 ?
Regds
AlanE
Oz
On 6/26/07, Antonio Soares <amsoares@netcabo.pt> wrote:
>
>
> Here's a capture i made a few weeks ago:
>
> +++++++++++++++++++++++++++++++++++++++++
> Frame 3 (118 bytes on wire, 118 bytes captured)
> Ethernet II, Src: Cisco_f6:f1:65 (00:17:0e:f6:f1:65), Dst: Cisco_c3:0d:38
> (00:15:63:c3:0d:38)
> 802.1Q Virtual LAN
> 000. .... .... .... = Priority: 0
> ...0 .... .... .... = CFI: 0
> .... 0000 0000 0000 = ID: 0
> Type: IP (0x0800)
> Internet Protocol, Src: 192.168.100.100 (192.168.100.100), Dst:
> 192.168.100.1 (192.168.100.1)
> Internet Control Message Protocol
> +++++++++++++++++++++++++++++++++++++++++
>
> This was the Switch config:
>
> !
> interface GigabitEthernet0/48
> switchport access vlan 333
> switchport mode dynamic desirable
> switchport voice vlan dot1p
> mls qos trust device cisco-phone
> spanning-tree portfast
> !
>
> These were my comments to the behaviour i saw:
>
> Data traffic untagged in and out, Voice traffic untagged out, tagged in
> with
> VLAN ID=0; PING DATA=OK, PING VOICE=OK
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Scott Morris
> Sent: segunda-feira, 25 de Junho de 2007 13:57
> To: 'M S'; acewer64@gmail.com; ccielab@groupstudy.com
> Subject: RE: Voice Vlan 0 - DOT1P
>
> If there is no dot1q tag, there is no dot1p priority field!
>
>
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
> #153, CISSP, et al.
> CCSI/JNCI-M/JNCI-J
> VP - Technical Training - IPexpert, Inc.
> IPexpert Sr. Technical Instructor
>
> A Cisco Learning Partner - We Accept Learning Credits!
>
> smorris@ipexpert.com
>
> Telephone: +1.810.326.1444
> Fax: +1.810.454.0130
> http://www.ipexpert.com <http://www.ipexpert.com/>
>
> _____
>
> From: M S [mailto:michaelgstout@hotmail.com]
> Sent: Monday, June 25, 2007 12:08 AM
> To: smorris@ipexpert.com; acewer64@gmail.com; ccielab@groupstudy.com
> Subject: RE: Voice Vlan 0 - DOT1P
>
>
>
> I was looking at this today. Can you let me know if i have it backwards?
> The 802.1p tag contains vlan 0, which is the native vlan. but when you
> connect the cisco phone to the cisco switch a trunk is automatically
> formed.
> With switchport interface command switchport access vlan 5, wouldn't the
> data traffic be tagged with vlan 5 and the 802.1p traffic be placed into
> the
> native vlan (vlan0)?
>
> THank You.
>
>
>
>
> _____
>
> From: "Scott Morris" <smorris@ipexpert.com>
> Reply-To: "Scott Morris" <smorris@ipexpert.com>
> To: "'Alan Ewer'" <acewer64@gmail.com>, "'Cisco certification'"
> <ccielab@groupstudy.com>
> Subject: RE: Voice Vlan 0 - DOT1P
> Date: Sun, 24 Jun 2007 21:59:21 -0400
> If you search Cisco's website (or Google) you'll find lots of references
> for
> VLAN 0 in regards to Voice VLANs. Basically, this is a designation for
> untagged frames, which means whatever your trunk's native VLAN is set to
> in
> the dot1q trunk to an IP phone, that's what VLAN 0 represents.
>
> That'll also mean it's the same VLAN as your PC's data behind the phone,
> and
> I'll tell you that's generally not a good idea in deployments. But this
> is
> all about the lab. :)
>
> So how about changing your voice vlan to something other than the default
> command set!
>
> To an IP phone, you SHOULD be trunking. The general spec is voice is
> tagged
> (dot1q), PC data is untagged (access vlan AKA your trunk's native vlan,
> untagged).
>
> HTH,
>
>
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
> #153, CISSP, et al.
> CCSI/JNCI-M/JNCI-J
> VP - Technical Training - IPexpert, Inc.
> IPexpert Sr. Technical Instructor
>
> A Cisco Learning Partner - We Accept Learning Credits!
>
> smorris@ipexpert.com
>
> Telephone: +1.810.326.1444
> Fax: +1.810.454.0130
> http://www.ipexpert.com <http://www.ipexpert.com/>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Alan
> Ewer
> Sent: Sunday, June 24, 2007 8:36 PM
> To: Cisco certification
> Subject: Voice Vlan 0 - DOT1P
>
> Hi all...
> sorry if this has been answered before.....
>
> I am playing around with voice vlans on 3550's
>
> When I invoke the "switch voice vlan dot1p" command I get a message
> referring to the voice VLAN being VLAN0, yet i cannot create/see VLAN 0
>
> So where is this mystical VLAN ? How do I use it and why is the voice
> traffic there ?? I would have thought that i would put it on the default
> native vlan for the interface (usually vlan 1) .....as usual the Cisco
> doco
> is unhelpful..and to some extent confusing (to me at least)...
>
> Also if voice vlan is 0 and access vlan is 1, doesnt this imply that the
> port is also trunking ??
>
>
> any explanation gratefully accepted..
>
> Regds
> AlanE
>
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