From: Lord, Chris (chris.lord@lorien.co.uk)
Date: Tue Aug 10 2004 - 06:40:49 GMT-3
Richard,
I don't know why option 2 is recommended over option 1, I've seen production configs using both methods with Cisco phones.
However, I believe you have a mistake in your options. I think the native vlan command belongs with option 1 not option 2.
In option1, assuming a Cisco phone is used and that a PC is connected into the back of the phone, the switch uses CDP to tell the phone which voice vlan is in use. The phone will send voice packets to the switch using .1q frames tagged with the specified voice vlan number. The phone will send PC packets to the switch untagged on the native vlan. Now, when the untagged native vlan frames hit the switch, the switch has to decide what to do with them. If you've designed your network where all of the PCs are in vlan 1 (the default native vlan) then you don't need the "sw native vl" command. However, I'm sure you are more sensible and have the PCs in another vlan so you need to notify the switch of this using the native vlan cmd. In option 1 the "sw access vlan" command has no purpose because the port is statically configured as a trunk port!
HTH,
Chris.
-----Original Message-----
From: Richard Anderson [mailto:richard.p.anderson@sbcglobal.net]
Sent: Monday, August 09, 2004 11:11 PM
To: swm@emanon.com; 'Elliott Reyes'; ccielab@groupstudy.com
Subject: Re: Vocie and Data VLANs
Scott,
You didn't answer to my question.
Thanks,
Richard
----- Original Message -----
From: "Scott Morris" <swm@emanon.com>
To: "'Elliott Reyes'" <elliottreyes@adelphia.net>; "'Richard Anderson'"
<richard.p.anderson@sbcglobal.net>; <ccielab@groupstudy.com>
Sent: Friday, August 06, 2004 7:03 AM
Subject: RE: Vocie and Data VLANs
> You don't. Per RFC's we have discussed, Avaya phones use the "evil bit"
in
> their voice packets and therefore will not interoperate with Cisco
> equipment.
>
> ;)
>
> You can still use the voice vlan command, but you must use the "switchport
> mode trunk" command to create trunking. You also must manually (in boot
> file or manually on the phone) set which VLAN is used for voice traffic.
>
> HTH,
>
>
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
> JNCIP, et al.
> IPExpert CCIE Program Manager
> IPExpert Sr. Technical Instructor
> swm@emanon.com/smorris@ipexpert.net
> http://www.ipexpert.net
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Elliott Reyes
> Sent: Thursday, August 05, 2004 11:40 PM
> To: 'Richard Anderson'; ccielab@groupstudy.com
> Subject: RE: Vocie and Data VLANs
>
> Suppose you had avaya phones plugged in in lieu of Cisco Phones
>
> How would you configure the ports to participate in a Voice vlan then ?
>
>
>
> E
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Richard Anderson
> Sent: Thursday, August 05, 2004 2:57 PM
> To: ccielab@groupstudy.com
> Subject: Vocie and Data VLANs
>
> There are two ways to configure voice and data vlan on a switch port:
>
> interface FastEthernet0/3
> switchport trunk encapsulation dot1q
> switchport mode trunk
> switchport voice vlan 31
> no ip address
> spanning-tree portfast trunk
> -----------------------------------------------------------------------
>
> Recommended:
>
> interface fastethernet 0/3
> switchport access vlan 10
> switchport voice vlan 20
> switchport native vlan 10
> spanning-tree portfast
>
> Couple of questions:
>
> Why 2nd choice is recommended?
> Why native vlan has to be changed from VLAN 1 to VLAN 10
>
> Thanks,
>
> Richard
>
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