VLAN Tagging PC Port 77xx and 88xx Series

[juergen_roesch]

Hello,

I've set VLAN to On, VLAN ID to 10, PC Port VLAN to 100 and pc port mirror to false

But the PC Port Packets are not tagged, the Phone-packets are tagged and PC port works, if vlan 100 on that port is set to untagged but never works if it has to be tagged.

Any Ideas whats wrong there?

Tryed with a 7821 and 8851 Phone

[Roger Kallberg]

There is nothing wrong with this, it is how it is supposed to work. The traffic coming from the PC port on the phone switch is always untagged, but set to be in the VLAN that is set as the access VLAN on the switch port the phone connects to.

[juergen_roesch]

Thanks for the reply.

but how does the setting of the PC Port VLAN ID makes sense?

[Roger Kallberg]

On the switch port that is North of the phone, ie the port in the switch the phone is connected to, you configure an access VLAN and a voice VLAN. This forms what is known as a pseudo trunk with the switch port on the phone and will “tell” the phone what VLANs to use for the phone and/or PC traffic. The traffic on the voice VLAN is tagged and the traffic on the access VLAN is not tagged. There are an abundance of documentation on this topic.

[Nithin Eluvathingal]

 

Hope this pic explains how it works 

[juergen_roesch]

that's clear so far, but in that picture, the switchport is set to VLAN 50 untagged that all untagged packets are sent to switch are tagged with vlan 50 at the switch port. So I don't understand what is the reaseon to set the VLAN 50 for the PC Port VLAN on the Phone? 

[Nithin Eluvathingal]

The port on switch side is not a trunk. its an access port with vlan 50. On the same access port we can define voice vlan which configured 25.

So The switch will treat all untaged packets as its coming from PC vlan 50.

Whats your port configurations on switch side ?

2.12.0.0

2.12.0.0

[niuoras01]

Sorry to revive this old topic, but I have the same question as the OP.  The diagram and explanations above state that the traffic from the phone itself will be tagged with the configured Voice VLAN (25 in the example), and the data traffic passed through from the phone's PC port will be untagged with VLAN 50 assigned at the switchport.  What I don't understand is, if the traffic from the phone's PC port towards the switch is untagged as shown, then what is the purpose of configuring the PC Port VLAN on the phone?  It could be configured to any value and it wouldn't matter since it's untagged.

[Roger Kallberg]

You do not do any configuration on the phone itself for VLANs. That is done on the switch port that the phone is connected to.

[Nithin Eluvathingal]

You don’t need to configure the PC port VLAN on the phone.

Configure the switch port access VLAN for the PC and the switch port voice VLAN for the phone on the port where you connect the phone to the switch.

[niuoras01]

Thanks,

So I assume this means the phone will get its VLAN configuration automatically from the switch using LLDP-MED, and I should leave the VLAN settings on the phone blank (VLAN ID and PC Port VLAN ID)?

Thanks

[Roger Kallberg]

Yes.

[Nithin Eluvathingal]

If you are using a Cisco phone connected to a Cisco switch, it uses CDP. If the phone is connected to a third-party switch, it will use LLDP.

By the way, what phone are you connecting and what switch are you using? Is your question related to a Cisco phone and Cisco switch?

[niuoras01]

I'm using a Cisco 7821 and 8851 running the 3PCC (3rd Party Call Control) software.  My switches are Unifi, which do support LLDP-MED and a voice VLAN, though I've never tried it before.  I guess we shall see if it works :-).