Please explain, what is het (best) procedure to configure Auto Voice VLAN?

[Boudewijn Plomp]

Dear Cisco,

Can you please explain what is the (best) procedure to configure Auto Voice VLAN???

Scenario:

Please allow me to explain what I am trying to achieve and the problem I encounter. First of all, I know how to configure Auto Voice VLAN. But I got weird behaviors and don't know if I "need" to change smarport types "native VLAN" settings. To makes things even weird, not all my switches behave the same. What I am trying to do is as following. I am sure I am doing something wrong.

I have one central SG300-28 switch in L3 mode. I also have seven SG300-10(P) switches in L2 mode functioning as access switches. These access swithes are connected to the central L3 switch using Link Aggregation. I also have IP Phones that don't support CDP, instead they support LLDP. The network hosts about 20 VLAN's. Two of them that are relevant are as following.

• VLAN 102 - Internal Network (Clients)
  
• VLAN 104 - Internal Network (Voice)
  

On the access switches I have configured port GE1 - GE8 as a trunk port. These trunk ports have a port VLAN membership 102U & 104T. I have also configured Auto Voice VLAN with VLAN ID 104.

Problem:

Now... Auto Voice VLAN works. IP Phones are automatically put into VLAN 104. But when you look at the port VLAN Membership it changes to 1U & 104T. Ok fine. But once I connect a desktop to the same port it does not connect to the network. For that I have experimented with the smartport macros. I have change the native_vlan to VLAN ID 102. At a certain point that seems to work. That is the way I have configured it. But it does not always work flawless. Sometimes the port is recognized as a desktop. Man o man, tried a lot got different things, with different results. To much information to explain you.

Questions:

• Each port should be configured a trunk port, right?
  
• Do you need to modify the smarport settings? If so, the auto_native VLAN ID should be 102, right?
  
• What else am I missing here?
  

Some information about this would be highly appreachiated.

[rmanthey]

Hello,

Yes all ports should be trunk ports that are connecting both phones and computers with the DATA vlan as Untagged and the Voice Vlan as Tagged.

I would recommend not using the Macro's manually and not touching any settings on the Smartport settings. If the switch is defaulted the following is all you need except the trunk settings per port.

config t
vlan database
vlan 102
vlan 104
exit
int vlan 102
name Clients
int vlan 104
name Voice
exit
voice vlan id 104
****   Answer Y(yes) *****
voice vlan state auto-enable

If you have an upstream switch you will need to make sure the same vlan id are used in the trunk and the native vlans will need to match.

Cisco Small Business Support Center

Randy Manthey

CCNA, CCNA - Security

[Boudewijn Plomp]

Randy,

Sorry, but apparently it doesn't seem to work that way.

I rarely use the command-line by the way. I already did and again did exactly what you say (via console). When the ports are configured as trunk ports with VLAN port membership 102UP / 104T. The following happens...

When you connect a computer all works fine and the computer gets into untagged data VLAN 102. Nothing is changed to the VLAN port membership. But when you connect an IP Phone it works fine and gets into the tagged Voice VLAN 104. But the VLAN port membership is suddenly changed to 1UP / 104T. The next time you connect a computer to that port it doesn't work and does not get an IP Address. Because the VLAN membership is changed to 1UP / 104T.

So... the bottomline is; smartport macro's do change something and thereby need to be configured when the port is configured as a turnk port. I assume it changes the VLAN port membership based on the the native_vlan ID defined in the smarpot macro. If I change changed native_vlan ID of the smartport macro's to the data VLAN ID, then things work much better. But not always as expected.

One thing to add I have noticed. When I change the trunk port to a general port. The VLAN membership stays unchanged. But... alway a but. When changing the cable from IP Phone to computer the smartport macro is sometimes disabled on the port. Very frustrating!

Any suggestions?

[rmanthey]

If you are experiancing those symptoms I would call the 1-866-606-1866 and have a case created for further diagnosics.

Cisco Small Business Support Center

Randy Manthey

CCNA, CCNA - Security

[Dan Miley]

a couple other configuration items might help,

in the smartports -  interface settings

set the port to 'ip phone + desktop'

is vlan 1 in use on your network? 

if not go to vlan management - interface settings and set your

administrative pvid to vlan 102

[Boudewijn Plomp]

Yes, VLAN ID 1 is already in use. It is the default management VLAN. All switches and wireless access points have an IP Address in that VLAN.

By the way. If you look at the smarport macro. The native_vlan$ parameter description says "The untag VLAN which will be configured on the port". So with other words. You need to set your data VLAN ID in there. Otherwise it will be changed to VLAN ID 1 instead.

There is nothing written about this in the manual.

[Dan Miley]

Actually it's better to set the 'native_vlan$' under

interface settings -- administrative pvid (primary vlan ID).  I can look up the CLI commands if needed.

rather than change the macro (as Randy mentioned).

It sounds like you may have a complex network configuration, but the switch shouldn't be behaving as you describe.

If you are still having difficulties, please call in and open a case so we can get it resolved.

Dan

[Boudewijn Plomp]

VLAN ID 1 is already used as the default management VLAN and I like to keep that unchanged.

Although it works (properly) by changing the native_vlan$ parameter value on each smartport macro it has a downside. You can never host different data VLAN's while using Auto Voice VLAN. Unless you use a seperate switch. Very unhandy.

I would like to know if it is better to configure each port as a general port. I don't know what is the advantage/disadvantage.

Sent from Cisco Technical Support iPad App

[Dan Miley]

sorry, I wrote it incorrectly

<< is vlan 1 in use on your network? >> 

should be

is vlan 1 the untagged network on that network segment? 

You can set the data vlan for THAT PORT through

vlan management - interface settings and set your

administrative pvid to vlan 102

This sets the untagged or native vlan FOR THAT PORT to 102. 

You still can have the admin interface of the switch on vlan 1,  but you can only have one untagged vlan per port as a general rule.

The administrative  pvid, becomes the default untagged vlan for that port.

as for general or trunk, the main differences are

the general mode allows ingress filtering, and allows filtering of tagged or untagged frame types.

Trunk mode automatically sets the pvid as the untagged vlan, where

in General mode you have to configure the untagged vlan also, supports mac based vlans.

The admin gude has a description of the vlan mode types

http://www.cisco.com/en/US/docs/switches/lan/csbms/sf30x_sg30x/administration_guide/78-19308-01.pdf

p 190 ish