Configuring VLAN Tagging for Voice Traffic

VLAN tagging is a method for identifying Ethernet frames so they can be transmitted on a specific virtual LAN. Network administrators often use VLAN tagging to separate out Voice over IP (VoIP) traffic so it can be prioritized ahead of other traffic. This helps to keep latency and jitter to a minimum so call quality can be maintained even when the network is busy.

The zero client supports VLAN tagging for voice traffic when the device is used as a PCoIP caller endpoint for CounterPath's Bria Virtualized Edition for PCoIP Zero Clients softphone client. (For more information about this softphone client, see Zero Client–to–Bria Softphone Caller Endpoint.)

System Requirements for VLAN Tagging

A zero client will automatically tag voice traffic during a Bria Virtualized Edition softphone VoIP call if your system meets the following requirements:

The zero client is enabled for DHCP (see Network Settings) so it can send requests to the DHCP server and receive responses from the server.
The zero client is enabled for Unified Communications (UC) support.
Your DHCP server supports option 60 (vendor class identifier) and option 43 (vendor-specific information).
Your DHCP server is configured to provide a Voice VLAN ID value in option 43. The configuration for this vendor-specific option is shown in the figure below:

DHCP Option 43 – Voice VLAN ID Option

When the zero client receives a DHCP offer that contains a Voice VLAN ID value in option 43, it will tag VoIP data with this value and send the traffic out on a secondary interface using the same MAC address that it uses for traffic on its primary interface.

The zero client's secondary interface supports IPv4 only and cannot be accessed via the AWI. However, when this interface is used for voice traffic, the zero client's event log will display the interface configuration, including its IP address, subnet mask, and default gateway. To see this information, search the event log for "sec_if_" entries, as shown in the sample search results below.

NOT FOUND:	sec_if_ip_address	=	10.0.157.122
NOT FOUND:	sec_if_subnet_mask	=	255.255.255.0
NOT FOUND:	sec_if_gateway	=	10.0.157.1
NOT FOUND:	sec_if_ip_address	=	10.0.157.122
NOT FOUND:	sec_if_primary_dns	=	192.168.65.2
NOT FOUND:	sec_if_seconary_dns	=	0.0.0.0

When Unified Communications support is enabled on the zero client, the event log will show "UC Provider: 1" for the uc_options entry, as shown below. When it is not enabled, it will show "UC Provider: 0".

IN FLASH:

uc_options

UC Provider: 1

To see the VLAN tag, search for "dhcp_get_pcoip_option43_vlan_id". The following example shows a VLAN tag of 1157.

MGMT_NET:

dhcp_get_pcoip_option43_vlan_id Voice VLAN is present ID =1157 (0x485)

Configuring DHCP Option 43

To configure a Windows 2008 DHCP server to send a Voice VLAN tag in option 43:

Open the DHCP Server console (Administrative Tools > DHCP).
Expand the tree for the server.
Right-click on IPv4 and select Define Vendor Classes.
Check your DHCP vendor classes and choose one of the following:
- Your DHCP server may already have a PCoIP Endpoint vendor class—for example, if you have previously set up DHCP options to configure PCoIP devices with the address of the Management Console for device discovery. If the PCoIP Endpoint vendor class displays in the Available classes list, as shown below, close the DHCP Vendor Classes dialog and go to step 7.
- If PCoIP Endpoint has not been added, click Add to add a new vendor class, and continue to the next step.
In the Display name field, enter PCoIP Endpoint, and add a description. Also add PCoIP Endpoint in the vendor ID ASCII column.
Click OK and then Close.
Right-click on IPv4 in the tree and select Set Predefined Options.
In the Option class field, select PCoIP Endpoint, and then click Add.
In the Option Type dialog, enter the following information:
1. Name: Voice VLAN ID
2. Data type: Word
3. Code: 4
4. Description: 16-bit identifier for the Voice VLAN
When you are finished, click OK.
In the Value field, enter a default value (in hexadecimal) for the Voice VLAN ID option.
If you want to set a different Voice VLAN ID value for a specific scope, expand the desired scope tree within your IPv4 tree.
Right-click on Scope Options and select Configure Options.
Click on the Advanced tab and select the PCoIP Endpoint vendor class.
Enable the check box for the 004 Voice VLAN ID option, and then enter a value in the Data entry field. This value will apply only to your selected scope.
Click OK.